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Cover Page - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
Cover Page - USD ($) $ / shares in Units, $ in Millions	Dec. 31, 2019	Feb. 28, 2020	Jun. 28, 2019	Dec. 31, 2018	Jan. 26, 2018
Cover page.
Document Transition Report	false
Document Type	10-K
Title of 12(b) Security	Common Stock
Document Quarterly Report	true
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	26-3039436
Entity Address, Address Line One	675 Ponce de Leon Ave. NE, Ste 6000
Entity Address, City or Town	Atlanta
Entity Address, State or Province	GA
Entity Address, Postal Zip Code	30308
City Area Code	(888)
Local Phone Number	792-5802
Trading Symbol	CDLX
Security Exchange Name	NASDAQ
Common stock, par or stated value per share (in usd per share)	$ 0.0001			$ 0.0001	$ 0.0001
Entity Central Index Key	0001666071
Entity Registrant Name	CARDLYTICS, INC.
Amendment Flag	false
Document Period End Date	Dec. 31, 2019
Entity File Number	001-38386
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	FY
Current Fiscal Year End Date	--12-31
Entity Filer Category	Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	true
Entity Ex Transition Period	false
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Shell Company	false
Entity Public Float			$ 455.3
Entity Common Stock, Shares Outstanding (in shares)		26,704,481

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Current assets:
Cash and cash equivalents	$ 104,458	$ 39,623
Accounts receivable, net	81,452	58,125
Other receivables	3,908	2,417
Prepaid expenses and other assets	5,783	3,956
Total current assets	195,730	124,368
Long-term assets:
Property and equipment, net	14,290	10,230
Intangible assets, net	389	370
Capitalized software development costs, net	3,815	1,625
Deferred FI implementation costs, net	8,383	15,877
Other long-term assets, net	1,706	1,293
Total assets	224,313	153,763
Current liabilities:
Accounts payable	1,229	2,099
Accrued liabilities:
Accrued compensation	8,186	5,936
Accrued expenses	6,018	4,388
FI Share liability	41,956	27,656
Consumer Incentive liability	19,861	11,476
Deferred billings	1,127	346
Current portion of long-term debt	24	21
Total current liabilities	78,401	51,922
Long-term liabilities:
Deferred liabilities	2,632	3,173
Long-term warrant liability	0
Long-term debt, net of current portion	13	46,693
Total liabilities	81,046	101,788
Stockholders’ (deficit) equity:
Common stock, $0.0001 par value—83,000 and 100,000 shares authorized and 3,439 and 22,466 shares issued and outstanding as of December 31, 2017 and December 31, 2018, respectively	8	7
Additional paid-in capital	480,578	371,463
Accumulated other comprehensive income	1,312	1,992
Accumulated deficit	(338,631)	(321,487)
Total stockholders’ (deficit) equity	143,267	51,975
Total liabilities and stockholders’ (deficit) equity	$ 224,313	153,763
Series G’ Stock
Redeemable convertible preferred stock:
Redeemable convertible preferred stock		0
Series G Stock
Redeemable convertible preferred stock:
Redeemable convertible preferred stock		0
Series F/F-R Stock
Redeemable convertible preferred stock:
Redeemable convertible preferred stock		0
Series E/E-R Stock
Redeemable convertible preferred stock:
Redeemable convertible preferred stock		0
Series D/D-R Stock
Redeemable convertible preferred stock:
Redeemable convertible preferred stock		0
Series C/C-R Stock
Redeemable convertible preferred stock:
Redeemable convertible preferred stock		0
Series B/B-R Stock
Redeemable convertible preferred stock:
Redeemable convertible preferred stock		0
Series A/A-R Stock
Redeemable convertible preferred stock:
Redeemable convertible preferred stock		$ 0

CONSOLIDATED BALANCE SHEETS (Parenthetical) - $ / shares	Dec. 31, 2019	Dec. 31, 2018	Jan. 26, 2018	Dec. 31, 2017	May 31, 2017	Feb. 28, 2017	Dec. 31, 2016
Redeemable convertible preferred stock, shares authorized (in shares)			25,000,000		96,131,002	82,683,212
Common stock, par or stated value per share (in usd per share)	$ 0.0001	$ 0.0001	$ 0.0001
Common stock, shares authorized (in shares)	100,000,000		100,000,000		83,000,000
Series G’ Stock
Redeemable convertible preferred stock, par value (in usd per share)					$ 0.0001
Redeemable convertible preferred stock, shares outstanding (in shares)		0		1,296,000
Series G Stock
Redeemable convertible preferred stock, par value (in usd per share)					$ 0.0001
Redeemable convertible preferred stock, shares outstanding (in shares)		0		346,000
Common stock, shares issued (in shares)					346,334
Series F/F-R Stock
Redeemable convertible preferred stock, shares outstanding (in shares)		0		1,199,000			1,199,000
Series E/E-R Stock
Redeemable convertible preferred stock, shares outstanding (in shares)		0		795,000			795,000
Series D/D-R Stock
Redeemable convertible preferred stock, shares outstanding (in shares)		0		1,396,000			1,396,000
Series C/C-R Stock
Redeemable convertible preferred stock, shares outstanding (in shares)		0		1,508,000			1,508,000
Series B/B-R Stock
Redeemable convertible preferred stock, shares outstanding (in shares)		0		2,247,000			2,247,000
Series A/A-R Stock
Redeemable convertible preferred stock, shares outstanding (in shares)		0		1,857,000			1,857,000

CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Statement [Abstract]
Revenue	$ 210,430	$ 150,684	$ 130,365
Costs and expenses:
FI Share and other third-party costs	118,080	85,371	73,247
Delivery costs	12,893	10,632	7,012
Sales and marketing expense	43,828	41,878	31,927
Research and development expense	11,699	16,210	12,150
General and administration expense	36,720	34,228	20,100
Depreciation and amortization expense	4,535	3,282	3,028
Total costs and expenses	227,755	191,601	147,464
Operating loss	(17,325)	(40,917)	(17,099)
Other (expense) income:
Interest expense, net	(548)	(3,264)	(8,239)
Change in fair value of warrant liabilities, net	0	(6,760)	(581)
Change in fair value of convertible promissory notes	0	0	(1,244)
Change in fair value of convertible promissory notes—related parties	0	0	6,213
Other (expense) income, net	729	(2,101)	1,309
Total other expense	181	(12,125)	(2,542)
Loss before income taxes	(17,144)	(53,042)	(19,641)
Income tax benefit	0	0	0
Net loss	(17,144)	(53,042)	(19,641)
Adjustments to the carrying value of redeemable convertible preferred stock	0	(157)	(5,743)
Net loss attributable to common stockholders	$ (17,144)	$ (53,199)	$ (25,384)
Net loss per share attributable to common stockholders, basic and diluted (in USD per share)	$ (0.72)	$ (2.79)	$ (7.86)
Weighted-average common shares outstanding, basic and diluted (in shares)	23,746	19,060	3,230

CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Statement of Comprehensive Income [Abstract]
Net loss	$ (17,144)	$ (53,042)	$ (19,641)
Other comprehensive income (loss):
Foreign currency translation adjustments	(680)	926	(1,036)
Total comprehensive loss	$ (17,824)	$ (52,116)	$ (20,677)

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References + Details

CONSOLIDATED STATEMENTS OF STOCKHOLDERS’ (DEFICIT) EQUITY - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-In Capital	Accumulated Other Comprehensive Income	Accumulated Deficit
Beginning balance (in shares) at Dec. 31, 2016		2,590,000
Beginning balance at Dec. 31, 2016	$ (216,835)	$ 0	$ 29,867	$ 2,102	$ (248,804)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of common stock options (in shares)		48,000
Exercise of common stock options	230		230
Stock-based compensation	5,147		5,147
Issuance of common stock warrants	312		312
Adjustments to Additional Paid in Capital, Dividends, Beneficial Conversion Feature	(4,488)		(4,488)
Deemed dividend related to beneficial conversion feature	4,488		4,488
Conversion to common stock (in shares)		801,000
Conversion to common stock	24,392		24,392
Accretion of redeemable stock	(1,255)		(1,255)
Other comprehensive income (loss)	(1,036)			(1,036)
Net loss	(19,641)				(19,641)
Ending balance (in shares) at Dec. 31, 2017		3,439,000
Ending balance at Dec. 31, 2017	(208,686)	$ 0	58,693	1,066	(268,445)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of common stock options (in shares)		356,000
Exercise of common stock options	$ 1,959		$ 1,959
Exercise of common stock warrants (in shares)	0	1,142,000	0
Stock-based compensation	$ 26,813		$ 26,813
Issuance of common stock (in shares)	1,296,000	5,821,000
Issuance of common stock	$ 66,101	$ 1	66,100
Issuance of common stock warrants	17,774		17,774
Issuance of ESPP	1,958	$ 177	1,958
Accretion of redeemable stock	(157)		(157)
Other comprehensive income (loss)	926			926
Net loss	(53,042)				(53,042)
Ending balance (in shares) at Dec. 31, 2018		22,466,000
Ending balance at Dec. 31, 2018	$ 51,975	$ 7	371,463	1,992	(321,487)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of common stock options (in shares)	716,000	716,000
Exercise of common stock options	$ 12,052		$ 12,052
Exercise of common stock warrants (in shares)	17,659,000	821,000	17,659,000
Stock-based compensation	$ 15,888		$ 15,888
Issuance of common stock (in shares)	486,000	1,904,000
Issuance of common stock	$ 61,309	$ 1	61,308
Issuance of ESPP (in shares)	267,823
Issuance of ESPP	$ 2,208	$ 154	2,208
Other comprehensive income (loss)	(680)			(680)
Net loss	(17,144)				(17,144)
Ending balance (in shares) at Dec. 31, 2019		26,547,000
Ending balance at Dec. 31, 2019	$ 143,267	$ 8	$ 480,578	$ 1,312	$ (338,631)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock Issued During Period, Shares, Restricted Stock Award, Gross		888,000

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Operating activities
Net loss	$ (17,144)	$ (53,042)	$ (19,641)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	4,535	3,282	3,028
Amortization of financing costs charged to interest expense	95	282	560
Accretion of debt discount and non-cash interest expense	0	2,326	6,889
Stock-based compensation expense	15,851	26,790	5,147
Change in the fair value of warrant liabilities, net	0	6,760	581
Change in the fair value of convertible promissory notes	0	0	1,244
Change in the fair value of convertible promissory notes - related parties	0	0	(6,213)
Other non-cash expense (income), net	631	4,771	(1,102)
Amortization of deferred FI implementation costs	2,869	1,618	1,626
Settlement of paid-in-kind interest	0	(8,353)	0
Change in operating assets and liabilities:
Accounts receivable	(26,018)	(9,426)	(7,503)
Prepaid expenses and other assets	(2,224)	(2,275)	(666)
Deferred FI implementation costs	0	(9,250)	(10,900)
Recovery of deferred FI implementation costs	4,625	5,380	4,100
Accounts payable	(601)	911	(1,907)
Other accrued expenses	6,152	3,255	466
FI Share liability	14,301	3,742	804
Customer Incentive liability	8,385	4,234	1,385
Net cash used in operating activities	11,457	(18,995)	(22,102)
Investing activities
Acquisition of property and equipment	(8,277)	(5,920)	(1,215)
Acquisition of patents	(31)	(23)	(60)
Capitalized software development costs	(2,712)	(1,399)	(372)
Net cash used in investing activities	(11,020)	(7,342)	(1,647)
Financing activities
Proceeds from issuance of debt	0	47,435	12,500
Principal payments of debt	(46,698)	(52,581)	(99)
Proceeds from issuance of common stock	91,216	72,334	230
Proceeds from issuance of Series G preferred stock	0	0	11,940
Equity issuance costs	(196)	(1,949)	(2,668)
Debt issuance costs	(143)	(48)	(142)
Net cash from financing activities	44,179	65,191	21,761
Effect of exchange rates on cash, cash equivalents and restricted cash	101	(246)	282
Net (decrease) increase in cash, cash equivalents and restricted cash	44,717	38,608	(1,706)
Cash, cash equivalents, and restricted cash — Beginning of period	59,870	21,262	22,968
Cash, cash equivalents, and restricted cash — End of period	104,587	59,870	21,262
Supplemental schedule of non-cash investing and financing activities:
Cash paid for interest	1,266	9,733	873
Amounts accrued for property and equipment	456	640	750
Amounts accrued for capitalized software development costs	10	0	61
Cash and cash equivalents	104,458	39,623	21,262
Restricted Cash and Cash Equivalents	$ 129	$ 20,247	$ 0

NATURE OF OPERATIONS	12 Months Ended
NATURE OF OPERATIONS	Dec. 31, 2019
Organization, Consolidation and Presentation of Financial Statements [Abstract]
NATURE OF OPERATIONS	Cardlytics, Inc. (“we,” “our,” “us,” the “Company,” or “Cardlytics”) is a Delaware corporation and was formed on June 26, 2008. We operate an advertising platform within financial institutions’ (“FIs”) digital channels, which include online, mobile, email, and various real-time notifications. Our partnerships with FIs provide us with access to their anonymized purchase data and digital banking customers. By applying advanced analytics to this aggregation of purchase data, we make it actionable, helping marketers identify, reach and influence likely buyers at scale, and measure the true sales impact of their marketing spend. We have strong relationships with leading marketers across a variety of industries, including national and regional restaurant and retail chains, large providers of cable satellite television and and wireless services, and increasingly, travel and hospitality, grocery, e-commerce and luxury brands. Using our purchase intelligence presents customers with offers to save money at a time when they are thinking of their finances. On May 4, 2012, we formed Cardlytics UK Limited (“Cardlytics UK”), a wholly-owned subsidiary registered as a private limited company in England and Wales. Cardlytics UK was a party to a collaboration agreement whereby 50% of its income and losses are shared with Aimia EMEA Limited (“Aimia”). Cardlytics, Inc. obtained full control of Cardlytics UK in June 2016 upon the termination of the cooperation agreement in exchange for convertible promissory notes of the Company. Refer to Note 6—Debt for additional information. We also operate in India through Cardlytics Services India Private Limited, a wholly-owned and operated subsidiary registered as a private limited company in India. Reverse Stock Split On January 26, 2018, our board of directors approved an amended and restated certificate of incorporation to (1) effect a reverse split on outstanding shares of our common stock and redeemable convertible preferred stock on a one-for-four basis (the “Reverse Stock Split”), (2) modify the threshold for automatic conversion of our preferred stock into shares of our common stock in connection with an initial public offering to eliminate the requirement of gross proceeds to the Company of not less than $70.0 million and (3) authorize us to issue up to 100,000,000 shares of common stock, $0.0001 par value per share and 25,000,000 shares of redeemable convertible preferred stock, $0.0001 par value per share (collectively, the “Charter Amendment”). The authorized shares and par values of our common stock and redeemable convertible preferred stock were not adjusted as a result of the Reverse Stock Split. The Charter Amendment was approved by the Company’s stockholders on January 26, 2018 and became effective upon the filing of the Charter Amendment with the State of Delaware on January 26, 2018. All issued and outstanding common stock and preferred stock and related share and per share amounts contained in these financial statements have been retroactively adjusted to reflect the Reverse Stock Split for all periods presented. Proceeds from Issuance of Common Stock On February 13, 2018, we closed our initial public offering (“IPO”), in which we issued and sold 5,400,000 shares of common stock at a public offering price of $13.00 per share, resulting in gross proceeds of $70.2 million. On February 14, 2018, pursuant to the underwriters’ partial exercise of their over-allotment option to purchase up to an additional 810,000 shares from us, we issued and sold an additional 421,355 shares of our common stock, resulting in additional gross proceeds to us of $5.5 million. In total, we issued 5,821,355 shares of common stock and raised $75.7 million in gross proceeds, or $66.1 million in net proceeds after deducting underwriting discounts and commissions of $5.3 million and offering costs of $4.3 million. Upon the closing of the IPO, all of the outstanding shares of redeemable convertible preferred stock automatically converted into shares of common stock and all warrants to purchase shares of redeemable convertible preferred stock were automatically converted into warrants to purchase shares of common stock. Subsequent to the closing of the IPO, there were no shares of preferred stock or warrants to purchase shares of redeemable convertible preferred stock outstanding. The consolidated financial statements as of December 31, 2017, including share and per share amounts, do not give effect to the IPO or conversion of the redeemable convertible preferred stock, as the IPO and such conversions were completed subsequent to December 31, 2017. Upon the completion of our IPO, our amended and restated certificate of incorporation authorized us to issue up to 100,000,000 shares of common stock, $0.0001 par value per share, and 10,000,000 shares of preferred stock, $0.0001 par value per share, all of which shares of preferred stock are undesignated. Our board of directors may establish the rights and preferences of the preferred stock from time to time. On September 13, 2019, we closed a public equity offering in which we sold 1,904,154 shares of common stock, which included 404,154 shares sold pursuant to the exercise by the underwriters of an option to purchase additional shares, at a public offering price of $34.00 per share. We received total net proceeds of $61.3 million after deducting underwriting discounts and commissions of $3.2 million and offering costs of $0.2 million. Selling stockholders, including certain of our executive officers and entities affiliated with certain of our directors, sold 1,194,365 shares of common stock in the offering at a public offering price of $34.00. We did not receive any proceeds from the sale of common stock by the selling stockholders. During 2017, 2018 and 2019, we received $0.2 million, $2.0 million and $29.7 million in proceeds from the exercise of options and warrants to purchase shares of common stock.

SIGNIFICANT ACCOUNTING POLICIES

12 Months Ended

Dec. 31, 2019

Accounting Policies [Abstract]

SIGNIFICANT ACCOUNTING POLICIES

Principles of Consolidation

The consolidated financial statements include the accounts of the Company and its wholly-owned subsidiaries. All intercompany transactions and balances have been eliminated in consolidation.

Use of Estimates

The preparation of financial statements in conformity with generally accepted accounting principles in the United States (“GAAP”) requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the consolidated financial statements. Actual results could differ from these estimates. Significant items subject to such estimates and assumptions include revenue recognition, internal-use software development costs, income taxes, stock-based compensation, income tax valuation allowance, contingencies and changes in fair value of our convertible promissory notes, preferred stock warrants and common stock warrants. We base our estimates on historical experience and also on assumptions that we believe are reasonable. Changes in facts or circumstances may cause us to change our assumptions and estimates in future periods and it is possible that actual results could differ from our current or revised future estimates.

Foreign Currency

The functional currency of our foreign wholly-owned subsidiaries is the local currency. We translate the financial statements of these subsidiaries into U.S. dollars each reporting period for purposes of consolidation. Assets and liabilities are translated at the period-end currency exchange rates, certain equity accounts are translated at historical exchange rates and income and expense amounts are translated at average currency exchange rates in effect for the period. The effect of these translation adjustments is reported in a separate component of stockholders’ deficit titled accumulated other comprehensive income.

We are also subject to gains and losses from foreign currency denominated transactions and the remeasurement of foreign currency denominated balance sheet accounts, both of which are included in other income (expense), net in the accompanying consolidated statements of operations. We recorded foreign currency (gains) losses totaling $(1.3) million and $1.2 million and $(0.8) million in 2017, 2018 and 2019, respectively.

FI Share and Other Third-Party Costs

With respect to Cardlytics Direct, we generally pay our FI partners a negotiated and fixed percentage of our billings to marketers less any Consumer Incentives that we pay to the FIs’ customers and certain third-party data costs ("FI Share"). FI Share and other third-party costs consist primarily of the FI Share that we pay our FI partners, media and data costs, and the amortization of implementation costs incurred pursuant to our agreements with certain FI partners, any incremental costs due to FIs as part of FI Share commitments, as well as a non-cash expense related to the vesting of warrants issued to an FI partner that accelerated upon the consummation of our IPO. To the extent that we use a specific FI customer’s anonymized purchase data in the delivery of our solutions, we pay the applicable FI partner an FI Share calculated based on the relative contribution of the data provided by the FI partner to the overall delivery of the services.

Delivery Costs

Delivery costs consist primarily of personnel-related costs of our campaign, data operations and production support teams, including salaries, benefits, bonuses and payroll taxes, as well as stock-based compensation expense. Delivery costs also include hosting facility costs, internally developed and purchased or licensed software costs, outsourcing costs and professional services costs.

Accounts Receivable

Accounts receivable are carried at the original invoiced amount less an allowance for doubtful accounts, determined based on the probability of future collection. When we become aware of circumstances that may decrease the likelihood of collection, we record a specific allowance against amounts due, which reduces the receivable to the amount that we believe will be collected. For all other accounts receivable, we determine the adequacy of the allowance based on historical loss patterns, the number of days that billings are past due and an evaluation of the potential risk of loss associated with specific accounts.

The following table presents changes in the allowance for doubtful accounts (in thousands):



	Year Ended December 31,
	2017			2018			2019
Beginning balance	$	653		$	105		$	169
Bad debt expense	73			130			1,201
Write-offs, net of recoveries	(621		)	(66		)	(1,115		)
Ending balance	$	105		$	169		$	255

Unbilled receivables were $0.1 million, $0.4 million and $0.6 million as of December 31, 2017, 2018 and 2019, respectively. An unbilled receivable represents revenue earned and recognized from customer activity that was not billed prior to the end of the reporting period. Unbilled receivables are included in accounts receivable, net on our consolidated balance sheets.

Property and Equipment

Property and equipment are stated at cost. Expenditures for maintenance and repairs are expensed as incurred, while betterments that materially extend the life of an asset are capitalized. The cost of assets sold, retired or otherwise disposed of, and the related accumulated depreciation, are eliminated from the accounts and any resulting gain or loss is recognized.

Depreciation of property and equipment is determined using the straight-line method over the estimated useful lives of the applicable assets, which are as follows:



Computer equipment:		2–3 years
Furniture and fixtures:		5 years
Leasehold improvements:		Lesser of estimated useful life or life of the lease

Intangible Assets

Intangible assets are recorded at cost and consist of costs incurred for software patent applications. As of December 31, 2019, we had four issued patents and are pursuing ten additional patents relating to our software. We received approval for three patents in 2013 and one patent in 2018 and began amortizing the costs of obtaining these patents over the estimated remaining lives of the patents. If a patent application is rejected or if we abandon efforts to obtain a new patent, all deferred patent costs are expensed immediately. Deferred patent costs related to patents for which we have not yet obtained approval totaled $0.2 million and $0.3 million as of December 31, 2018 and 2019, respectively. Based on deferred patent costs as of December 31, 2019, the related amortization expense will be less than $0.1 million in each of the next five years. Intangible assets are as follows (in thousands):



	December 31,
	2018			2019
Deferred patent costs, gross	$	417		$	448
Less accumulated amortization	(47		)	(59		)
Deferred patent costs, net	$	370		$	389

Internal-Use Software Development Costs

Capitalized software development costs consist of costs incurred in the development of internal-use software, primarily associated with the development and enhancement of our offer management system and offer placement system. We capitalize the costs of software developed or obtained for internal use in accordance with ASC Topic 350-40, Internal Use Software. We begin to capitalize our costs upon completion of the preliminary project stage. We consider the preliminary project stage to be complete and the application development stage to have begun when preliminary development efforts are successfully completed, management has authorized and committed project funding and it is probable that the project will be completed and the software will be used as intended. These costs are amortized on a straight-line basis over the estimated useful life of the related asset, generally estimated to be three years. Costs incurred in the preliminary project stage and post-implementation operation stages are expensed as incurred and recorded in research and development expense on our consolidated statements of operations.

During 2017, 2018 and 2019, we capitalized development costs for enhancements to our offer management system as well as the implementation of a new billing system totaling $0.4 million, $1.6 million and $2.6 million, respectively.

Capitalized software development costs are as follows (in thousands):



	December 31,
	2018			2019
Capitalized software development costs, gross	$	2,826		$	5,537
Less accumulated amortization	(1,201		)	(1,722		)
Capitalized software development costs, net	$	1,625		$	3,815

Debt Issuance Costs

Costs incurred to obtain loans, other than lines of credit, are recorded as a reduction of the carrying amount of the related liability and amortized over the applicable loans’ life using the effective interest method. Costs incurred to obtain lines of credit are capitalized and included in other long-term assets on our consolidated balance sheets and amortized ratably over the term of the arrangement. Costs incurred to obtain loans for which we have elected the fair value option are expensed upon the issuance of the loan and recorded within general and administrative expense on our consolidated statements of operations.

As described in Note 6—Debt, we entered into a 2018 Loan Facility in 2018 and deferred $0.1 million of debt issuance costs associated with obtaining the 2018 Loan Facility and deferred $0.1 million of unamortized debt issuance costs attributed to our 2016 Line of Credit and 2016 Term Loan. We recognized a $0.9 million loss on extinguishment of debt related to the unamortized discount and unamortized debt issuance costs associated with our 2016 Term Loan and 2016 Line of Credit. This expense is included within other income (expense), net on our consolidated statements of operations and is presented in other non-cash expenses on our consolidated statement of statement of cash flows.

Amortization of debt issuance costs included in interest expense, net totaled $0.6 million, $0.3 million and $0.1 million in 2017, 2018 and 2019, respectively.

Deferred debt issuance costs related to our lines of credit included in other long-term assets are as follows (in thousands):



	December 31,
	2018			2019
Debt issuance costs, gross	$	334		$	388
Less accumulated amortization	(234		)	(271		)
Debt issuance costs, net	$	100		$	117

Deferred debt issuance costs related to our term loans included in debt are as follows (in thousands):



	December 31,
	2018			2019
Debt issuance costs, gross	$	30		$	—
Less accumulated amortization	(10		)	—
Debt issuance costs, net	$	20		$	—

Future amortization of debt issuance costs is as follows (in thousands):



Years Ending December 31,	Amortization
2020	$	87
2021	30
Total	$	117

Deferred Offering Costs

Deferred offering costs consist of incremental costs directly attributable to equity offerings. Deferred offering costs are included in other long-term assets on our consolidated balance sheets. Upon completion of an offering, these amounts are offset against the proceeds of the offering.

Deferred offering costs is as follows (in thousands):



	Year Ended December 31,
	2017		2018			2019
Beginning balance	$	—	$	3,144		$	—
Deferred costs	3,144		1,135			196
Recognized against offering proceeds	—		(4,279		)	(196		)
Ending balance	$	3,144	$	—		$	—

Advertising

We expense advertising costs as incurred. These costs are included in sales and marketing expense on our consolidated statements of operations. Advertising costs include direct marketing costs such as print advertisements, market research, direct mail, public relations and trade show expenses and totaled $0.7 million, $0.9 million and $1.4 million in 2017, 2018 and 2019, respectively.

Stock-Based Compensation

We measure and recognize compensation expense based on the estimated fair value of the award on the grant date. The fair value is recognized as expense over the requisite service period, which is generally the vesting period of the respective award, on a straight-line basis when the only condition to vesting is continued service. We recognize the fair value of awards that contain performance conditions based upon the probability of the performance conditions being met. Expense for awards with performance conditions are estimated and adjusted on a quarterly basis based upon our assessment of the probability that the performance condition will be met. We recognize the fair value of awards that contain market conditions over the derived service period. Forfeitures are accounted for when they occur. Refer to Note 7—Stock-based Compensation for additional information regarding our specific award plans and estimates and assumptions used to determine fair value.

Redeemable Convertible Preferred Stock Warrant Liability

Warrants to purchase shares of our redeemable convertible preferred stock are accounted for as derivative liabilities in accordance with ASC Topic 815, Derivatives and Hedging due to the terms of the warrants and related agreements. We have determined that these warrants do not meet the scope exception of a contract indexed to our stock because of fair value protections contained in agreements governing our redeemable convertible preferred stock as described in Note 9—Redeemable Convertible Preferred Stock. We record preferred stock warrant liabilities on our consolidated balance sheets at their fair value. We record the changes in fair value of such instruments as non-cash gains or losses on our statements of operations. Upon the consummation of our IPO, all of the outstanding warrants to purchase shares of redeemable convertible preferred stock were automatically converted into warrants to purchase shares of common stock. Refer to Note 11—Fair Value Measurements for additional information.

Common Stock Warrant Liability

In connection with the Series G Stock financing, we issued warrants to purchase shares of our common stock that are accounted for as liabilities in accordance with ASC Topic 480, Distinguishing Liabilities From Equity due to the terms of the warrants and related agreements. We record these common stock warrant liabilities on our consolidated balance sheets at their fair value. We record the changes in fair value of such instruments as non-cash gains or losses in our statements of operations. Refer to Note 11—Fair Value Measurements for additional information.

Fair Value of Financial Instruments

When required by GAAP, assets and liabilities are reported at fair value on our consolidated financial statements. Fair value is defined as the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. Valuation techniques used to measure fair value must maximize the use of observable inputs and minimize the use of unobservable inputs. Valuation inputs are arranged in a hierarchy that consists of the following levels:


•	Level 1 inputs are quoted prices (unadjusted) in active markets for identical assets or liabilities that the reporting entity has the ability to access at the measurement date.

•

Level 2 inputs are inputs other than Level 1 inputs such as quoted prices for similar assets or liabilities; quoted prices in markets with insufficient volume or infrequent transactions (less active markets); or model-derived valuations in which all significant inputs are observable or can be derived principally from or corroborated by observable market data for substantially the full term of the assets or liabilities.


•	Level 3 inputs are unobservable inputs for the asset or liability.

Our nonfinancial assets that we recognize or disclose at fair value on our consolidated financial statements on a nonrecurring basis include property and equipment, intangible assets, capitalized software development costs and deferred FI implementation costs. The fair values for these assets are evaluated when events or changes in circumstances indicate the carrying value may not be recoverable.

Convertible Promissory Notes

The redemption features included in the terms of the convertible promissory notes were determined to be derivative liabilities as a result of a significant discount within the redemption features for the note holders. Embedded derivatives that are not clearly and closely related to the host contract are required to be bifurcated and recorded at fair value unless the fair value option is elected on the host contract. Under the fair value option, bifurcation of the embedded derivative is not necessary as all related gains or losses on the host contract and derivative will be reflected on the consolidated statements of operations. We elected the fair value option for the convertible promissory notes upon their issuance. The convertible promissory notes are measured at fair value using unobservable inputs that required a high level of judgment, and are therefore classified as Level 3. In May 2017, we issued and sold shares of Series G redeemable convertible preferred stock, which resulted in the conversion of the convertible promissory notes into either shares of our common stock or shares of our Series G’ Stock. Refer to Note 11—Fair Value Measurements for additional information regarding the valuation of the convertible promissory notes.

Income Taxes

Income taxes are accounted for using the asset and liability method. Under this method, deferred tax assets and liabilities are recognized for the future tax consequences attributable to differences between the financial statement carrying amounts of existing assets and liabilities and their respective income tax bases, and operating loss and tax credit carryforwards. Valuation allowances are provided when we determine that it is more likely than not that all of, or a portion of, deferred tax assets will not be utilized in the future.

Significant judgment is required in determining any valuation allowance recorded against deferred tax assets. In assessing the need for a valuation allowance, we consider all available evidence, including past operating results, estimates of future taxable income and the feasibility of tax planning strategies. In the event that we change our determination as to the amount of deferred tax assets that can be realized, we will adjust our valuation allowance with a corresponding impact to the provision for income taxes in the period in which such determination is made.

Estimates of future taxable income are based on assumptions that are consistent with our plans. Assumptions represent management’s best estimates and involve inherent uncertainties and the application of management’s judgment. If actual amounts differ from our estimates, the amount of our tax expense and liabilities could be materially impacted.

We have recorded a full valuation allowance related to our net deferred tax assets due to the uncertainty of the ultimate realization of the future benefits of those assets.

We recognize the tax effects of an uncertain tax position only if it is more likely than not to be sustained based solely on its technical merits as of the reporting date, and then, only in an amount more likely than not to be sustained upon review by the tax authorities. Where applicable, we classify associated interest and penalties as income tax expense. The total amounts of interest and penalties were not material. We consider many factors when evaluating and estimating our tax positions and tax benefits, which may require periodic adjustments and which may not accurately anticipate actual outcomes.

On December 22, 2017, the Tax Cuts and Jobs Act of 2017 (“Tax Act”) was signed into law making significant changes to the Internal Revenue Code of 1986, as amended (“IRC”). Changes include, but are not limited to, a corporate tax rate decrease to 21% effective for tax years beginning after December 31, 2017. This change in tax rate resulted in a reduction in our net U.S. deferred tax assets, which was fully offset by a reduction in our valuation allowance. The other provisions of the Tax Act, including the one-time transition tax on the mandatory deemed repatriation of cumulative foreign earnings, did not have a material impact on our financial statements.

ACCOUNTING STANDARDS	12 Months Ended
ACCOUNTING STANDARDS	Dec. 31, 2019
Accounting Policies [Abstract]
ACCOUNTING STANDARDS	ACCOUNTING STANDARDS Recently Adopted Accounting Pronouncements On January 1, 2019, we early adopted Accounting Standards Update (“ASU”) 2014-09, Revenue from Contracts with Customers (Topic 606), using the modified retrospective method, as permitted under ASU 2014-09. The adoption of ASU 2014-09 did not result in a material change in the timing or amount of revenue recognized, nor did it result in the capitalization of incremental contract costs. Accordingly, there was no cumulative effect adjustment recorded in the consolidated financial statements upon adoption. On January 1, 2019, we adopted ASU 2016-01, Financial Instruments-Overall (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities, which is intended to enhance the reporting model for financial instruments to provide users of financial statements with more decision-useful information. The adoption of this guidance had no impact on our consolidated financial statements. Recently Issued Accounting Pronouncements In April 2015, the FASB issued ASU 2015-05, Intangibles—Goodwill and Other—Internal-Use Software (Subtopic 350-40): Customer’s Accounting for Fees Paid in a Cloud Computing Arrangement, to help entities evaluate the accounting for fees paid by a customer in a cloud computing arrangement (hosting arrangement) by providing guidance for determining when the arrangement includes a software license. If a cloud computing arrangement includes a license to internal-use software, then the software license is accounted for by the customer in accordance with Subtopic 350-40. This generally means that an intangible asset is recognized for the software license and, to the extent that the payments attributable to the software license are made over time, a liability also is recognized. If a cloud computing arrangement does not include a software license, the entity should account for the arrangement as a service contract. This generally means that the fees associated with the hosting element (service) of the arrangement are expensed as incurred. For public entities, this ASU is effective for fiscal years beginning after December 15, 2019, and interim periods within those fiscal years. For non-public entities, this ASU is effective for fiscal years beginning after December 15, 2020, and interim periods within fiscal years beginning after December 15, 2021. Early adoption is permitted, including adoption in any interim period, for all entities. We have made the election to use the extended transition period for complying with new or revised accounting standards under Section 102(b)(1) of the JOBS Act, and therefore we will be required to adopt this ASU for annual reporting periods beginning after December 15, 2020. We early adopted this ASU on January 1, 2020 on a prospective basis. We do not expect the adoption to have a material effect on our consolidated financial statements. In February 2016, the FASB issued ASU 2016-02, Leases (Topic 842), which supersedes ASC Topic 840, Leases. The ASU does not significantly change the lessees’ recognition, measurement and presentation of expenses and cash flows from the previous accounting standard. The ASU requires lessees to recognize a lease liability for payments and a right of use asset representing the right to use the leased asset during the term on operating lease arrangements. Lessees are permitted to make an accounting policy election to not recognize the asset and liability for leases with a term of twelve months or less. Lessors’ accounting under the ASU is largely unchanged from the previous accounting standard. In addition, the ASU expands the disclosure requirements of lease arrangements. In July 2018, the FASB issued ASU 2018-11, Leases (Topic 842) - Targeted Improvements, which provides the option of applying the requirements of the new lease standard in the period of adoption with no restatement to comparative periods. For public entities, Leases (Topic 842) is effective for fiscal years beginning after December 15, 2018, including interim periods within those fiscal years. In November 2019, the FASB issued ASU 2019-10, Leases (Topic 842), making the effective date of Leases (Topic 842) for non-public entities effective for annual periods beginning after December 15, 2020, and interim periods within fiscal years beginning after December 15, 2021. We have made the election to use the extended transition period for complying with new or revised accounting standards under Section 102(b)(1) of the JOBS Act, and therefore we will be required to adopt this ASU for annual reporting periods beginning after January 1, 2021. Early adoption is permitted. Although we are currently evaluating the impact of this guidance on our consolidated financial statements, we expect that most of our operating lease commitments will be recognized as operating lease liabilities and right-of-use assets upon adoption of the new guidance.

PROPERTY AND EQUIPMENT

12 Months Ended

Dec. 31, 2019

Property, Plant and Equipment [Abstract]

PROPERTY AND EQUIPMENT

Significant components of property and equipment are as follows (in thousands):



	December 31,
	2018			2019
Computer equipment	$	16,284		$	21,269
Leasehold improvements	5,573			6,960
Furniture and fixtures	913			1,557
Construction in progress	65			1,125
Property and equipment, gross	22,835			30,911
Less accumulated depreciation	(12,605		)	(16,621		)
Property and equipment, net	$	10,230		$	14,290

Assets acquired under capital leases, included within computer equipment, are as follows (in thousands):



	December 31,
	2018			2019
Capital lease assets, gross	$	1,096		$	1,096
Less accumulated depreciation	(1,047		)	(1,067		)
Capital lease assets, net	$	49		$	29

Depreciation expense was $3.0 million, $3.0 million and $4.0 million in 2017, 2018 and 2019, respectively.

DEBT

12 Months Ended

Dec. 31, 2019

Debt Disclosure [Abstract]

DEBT

Our debt consists of the following (in thousands):



	December 31,
	2018			2019
Lines of credit	$	26,677		$	—
Term loans	19,980			—
Capital leases	57			37
Total debt	46,714			37
Less current portion of long-term debt	(21		)	(24		)
Long-term debt, net of current portion	$	46,693		$	13

We had no accrued interest in debt as of December 31, 2018 and 2019, respectively. Paid-in-kind interest related to the convertible promissory notes is recognized in interest expense, net on our consolidated statements of operations and totaled $1.7 million during 2017.

2018 Loan Facility

On May 21, 2018, we entered into a Loan and Security Agreement with Pacific Western Bank (the “Lender”) consisting of a $30.0 million asset–based revolving line of credit ("2018 Line of Credit") and a $20.0 million term loan ("2018 Term Loan") (collectively, the “2018 Loan Facility”). We used the entire $20.0 million in proceeds from the 2018 Term Loan and an advance of $27.4 million under the 2018 Line of Credit to repay all outstanding obligations under our prior line of credit and term loan.

On May 14, 2019, we amended our 2018 Loan Facility to increase the capacity of our Line of Credit, from $30.0 million to $40.0 million, and decrease the capacity of our 2018 Term Loan from $20.0 million to $10.0 million. This amendment also extended the maturity date of the 2018 Loan Facility from May 21, 2020 to May 14, 2021. We repaid $10.0 million of the principal balance of the 2018 Term Loan upon the execution of the amendment in May 2019 and repaid the remaining $10.0 million principal balance in September 2019. As of December 31, 2019, we had $40.0 million of unused borrowings available under our 2018 Line of Credit.

The 2018 Loan Facility contains moving trailing 12-month billing covenants, which range from $210.0 million to $255.0 million, during the term of the facility. The moving 12-month billings covenant was $240.0 million for December 2019. The 2018 Loan Facility also requires us to maintain a total cash balance plus liquidity under the 2018 Line of Credit of not less than $5.0 million.

Under the 2018 Loan Facility relating to the 2018 Line of Credit, we are able to borrow up to the lesser of $40.0 million or 85% of the amount of our eligible accounts receivable. Interest on advances under the 2018 Line of Credit bears an interest rate equal to the prime rate minus 0.50%, or 4.25% as of December 31, 2019. In addition, we are required to pay an unused line fee of 0.15% per annum on the average daily unused amount of the $40.0 million revolving commitment. Interest accrued on the 2018 Term Loan at an annual rate of interest equal to the prime rate minus 2.75%, or 2.00% at the date of repayment in September 2019.

The 2018 Loan Facility includes customary representations, warranties and covenants (affirmative and negative), including restrictive covenants that prohibits mergers, acquisitions and dispositions of assets, incurrence of indebtedness and encumbrances on our assets and the payment or declaration of dividends; in each case subject to specified exceptions.

The 2018 Loan Facility also includes standard events of default, including in the event of a material adverse change. Upon the occurrence of an event of default, the lender may declare all outstanding obligations immediately due and payable and take such other actions as are set forth in the 2018 Loan Facility and increase the interest rate otherwise applicable to advances under the 2018 Line of Credit by an additional 3.00%. All of our obligations under the 2018 Loan Facility are secured by a first priority lien on substantially all of our assets. The 2018 Loan Facility does not include any prepayment penalties.

We believe we were in compliance with all financial covenants as of December 31, 2019.

2016 Line of Credit

In September 2016, we entered into a $50.0 million loan and security agreement ("2016 Line of Credit") maturing on March 14, 2019. The 2016 Line of Credit facility was repaid and terminated in May 2018 in connection with obtaining our 2018 Loan Facility. We recognized a $0.1 million loss on extinguishment of debt related to the unamortized debt issuance costs. This expense is included within other income (expense), net in our consolidated statements of operations and is presented in other non-cash expenses on our consolidated statement of statement of cash flows.

2016 Term Loan

In July 2016, we entered into a $24.0 million credit agreement ("2016 Term Loan") maturing on July 21, 2019. The 2016 Term Loan was repaid and terminated in May 2018 in connection with obtaining our 2018 Loan Facility. We recognized a $0.8 million loss on extinguishment of debt related to the unamortized discount and unamortized debt issuance costs. This expense is included within other income (expense), net in our consolidated statements of operations and is presented in other non-cash expenses on our consolidated statement of statement of cash flows.

Convertible Promissory Notes

During 2016, we issued unsecured convertible promissory notes to existing stockholders and Aimia with an aggregate principal amount of $50.7 million. The redemption features included in the terms of the convertible promissory notes were determined to be derivative liabilities as a result of a significant discount within the redemption features for the note holders. Embedded derivatives that are not clearly and closely related to the host contract are required to be bifurcated and recorded at fair value unless the fair value option is elected on the host contract. Under the fair value option, bifurcation of the embedded derivative is not necessary as all related gains (losses) on the host contract and derivative will be reflected in the consolidated statements of operations. We elected the fair value option for the convertible promissory notes and changes in fair value of the convertible promissory notes are included in change in fair value of convertible promissory notes on our consolidated statements of operations. Refer to Note 11—Fair Value Measurements for additional information regarding the valuation of the convertible promissory notes.

Existing Stockholder Notes

During 2016, we issued unsecured convertible promissory notes to certain of our existing stockholders with an aggregate principal amount of $27.0 million ("Existing Stockholder Notes"). In May 2017, we issued and sold shares of Series G redeemable convertible preferred stock, which resulted in the conversion of the Existing Stockholder Notes into shares of our Series G’ Stock. Refer to Note 9—Redeemable Convertible Preferred Stock for additional information regarding the Series G Stock financing and the transactions that resulted in the conversion of the Existing Stockholder Notes into shares of our Series G’ Stock.

Aimia Notes

During 2016, we issued to Aimia unsecured convertible promissory notes (“Aimia EMEA Notes”), in an aggregate principal amount of $18.0 million. In consideration for our outstanding obligations to Aimia Inc. at the time we terminated our U.K. cooperation agreement, we issued to Aimia an unsecured convertible promissory note (“Outstanding Obligation Note”) in an aggregate principal amount of approximately $5.7 million.

Both the Aimia EMEA Notes and the Outstanding Obligation Note (collectively the “Aimia Notes”) were convertible into shares of our capital stock, depending on certain triggering events. In the event we completed an equity financing in which we received proceeds in excess of $10.0 million, the Aimia EMEA Notes were to automatically convert into shares of our common stock and the Outstanding Obligation Note was to automatically convert into shares of the same series of our capital stock as the investors in the financing.

In connection with the Series G Stock financing, the Aimia EMEA Notes converted into 801,329 shares of common stock. Refer to Note 9—Redeemable Convertible Preferred Stock for additional information of the Series G Stock financing and the transactions that resulted in the conversion of the Aimia EMEA Notes into shares of our common stock and the conversion of the Outstanding Obligation Note into shares of our Series G’ Stock.

Future Payments

Aggregate future payments of principal and interest due upon maturity are as follows (in thousands):



Years Ending December 31,	Capital leases
2020	$	24
2021	13
Total debt	$	37

STOCK-BASED COMPENSATION

12 Months Ended

Dec. 31, 2019

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

STOCK-BASED COMPENSATION

In May 2017, our board of directors and stockholders approved an increase in the total number of shares of common stock issuable under our 2008 Stock Plan ("2008 Plan") from 3,120,000 to 3,495,000 shares. In January 2018, our board of directors and stockholders approved an increase in the total number of shares of common stock issuable under our 2008 Plan to 4,020,000 shares.

Our board of directors has adopted and our stockholders have approved our 2018 Equity Incentive Plan ("2018 Plan"). Our 2018 Plan became effective on February 8, 2018, the date our registration statement in connection with our IPO was declared effective. We do not expect to grant any additional awards under the 2008 Plan. Any awards granted under the 2008 Plan will remain subject to the terms of our 2008 Plan and applicable award agreements.

Initially, the aggregate number of shares of our common stock that may be issued pursuant to stock awards under the 2018 Plan was the sum of (i) 1,875,000 shares plus (ii) 61,247 shares reserved, and remaining available for issuance, under our 2008 Plan at the time our 2018 Plan became effective and (iii) the number of shares subject to stock options or other stock awards granted under our 2008 Plan that would have otherwise returned to our 2008 Plan (such as upon the expiration or termination of a stock award prior to vesting). As of December 31, 2019, there were 1,345,631 shares of our common stock reserved for issuance under our 2018 Plan. The number of shares of our common stock reserved for issuance under our 2018 Plan will automatically increase on January 1 of each year, beginning on January 1, 2019 and continuing through and including January 1, 2028, by 5% of the total number of shares of our capital stock outstanding on December 31 of the preceding calendar year, or a lesser number of shares determined by our board of directors. Accordingly, the number of shares of our common stock reserved for issuance under our 2018 Plan increased by 1,327,352 shares on January 1, 2020.

The 2018 Plan provides for the grant of stock options, stock appreciation rights, restricted stock awards, restricted stock unit awards, performance-based stock awards and other forms of equity compensation, which are collectively referred to as stock awards. Additionally, the 2018 Plan provides for the grant of performance cash awards.

The following table summarizes the allocation of stock-based compensation on the consolidated statements of operations (in thousands):



	Year Ended December 31,
	2017		2018		2019
Delivery costs	$	202	$	633	$	711
Sales and marketing expense	1,894		9,358		4,248
Research and development expense	951		4,087		1,619
General and administration expense	2,100		12,712		9,273
Total stock-based compensation expense	$	5,147	$	26,790	$	15,851

During 2017, 2018 and 2019, we capitalized less than $0.1 million of stock-based compensation expense for software development.

Common Stock Options

The term of each option to purchase shares of our common stock pursuant to the Stock Plan is set by our board of directors or a committee thereof. Option awards are generally granted with an exercise price not less than the fair value per share of our common stock at the grant date. Option awards generally vest over four years and expire 10 years following the date of grant.

A summary of common stock option activity is as follows (in thousands, except per share amounts):



	Shares		Weighted-Average Exercise Price Per Share		Weighted Average Contractual Life (in years)	Aggregate Intrinsic Value⁽¹⁾(in thousands)
Outstanding - December 31, 2018	1,774		$	20.55
Granted	39		20.64
Exercised	(716	)	16.84			21,399
Forfeited	(31	)	23.95
Cancelled	(66	)	22.37
Outstanding - December 31, 2019	1,000		$	22.99	6.51	$	39,894
Exercisable - December 31, 2019	757		$	22.45	6.29	$	30,586


(1)	The aggregate intrinsic value represents the total pre-tax intrinsic value based on the $62.86 closing price of our common stock as reported on the Nasdaq Global Market on December 31, 2019 that would have been received by option holders had all in-the-money options been exercised on that date.

The total fair value of options vested during 2017, 2018 and 2019 was approximately $4.3 million, $6.0 million and $4.8 million, respectively. As of December 31, 2019, $2.8 million of unrecognized compensation expense related to unvested options will be recognized over a weighted-average period of 1.1 years. All stock option awards outstanding as of December 31, 2019 are expected to vest.

During 2017, we granted 799,129 options to purchase shares of our common stock to employees with a weighted-average exercise price of $23.78 per share. We determined that a retrospective valuation of the fair value of our common stock on each grant date in 2017 was appropriate for financial reporting purposes. In connection with the preparation of our retrospective valuation, we noted that the fair value of our common stock, as determined by contemporaneous third-party valuations, was $24.48 per share on December 31, 2016, $27.68 per share on February 28, 2017, $30.44 per share on May 15, 2017 and $24.24 per share on September 30, 2017. The changes in fair value of our common stock primarily resulted from the dilutive effect of our Series G Stock financing, the timing of future potential liquidity events, changes to our forecasted financial results and changes in the valuation of comparable companies. We derived the fair value of our common stock on December 31, 2017 using a similar interpolation methodology and determined the fair value of our common stock to be $26.74 per share.

We determine the grant date fair value of options using the Black-Scholes option pricing model, which is affected by the estimated fair value of our common stock as well as the following significant inputs:



	Year Ended December 31,
	2017
Weighted-average grant date fair value	$12.11
Significant inputs:
Value of common stock	$24.60 - $28.16
Expected term	7.0 years
Volatility	50% to 51%
Risk-free interest rate	0.7% - 2.2%

Restricted Stock Units

We grant restricted stock units ("RSUs") to employees and our non-employee directors. A summary of RSU activity, inclusive of performance-based RSUs, is as follows (in thousands, except per share amounts):



	Shares		Weighted-Average Grant Date Fair Value Per Share		Weighted-Average Remaining Contractual Term (in years)	Unamortized Compensation Costs (in thousands)
Unvested - December 31, 2017	—		$	—
Granted	1,309		20.58
Vested	(850	)	21.93
Forfeited/canceled	(78	)	17.97
Unvested - December 31, 2018	381		$	18.11
Granted	1,978		17.78
Vested	(486	)	14.97
Forfeited	(132	)	18.92
Unvested - December 31,2019	1,741		$	18.55
Expected to Vest	1,428		$	19.22	3.09	$	20,389

Service-based Restricted Stock Units

During 2018, we granted 434,377 RSUs to our employees and non-employee directors, which have annual vesting periods ranging from one to four years. As of December 31, 2018, there was approximately $4.5 million of unrecognized compensation expense related to RSUs, which is expected to be recognized over a weighted-average period of 2.4 years.

During 2019, we granted 725,832 RSUs to employees and our non-employee directors, which have annual vesting periods ranging from one to four years. As of December 31, 2019, there was approximately $20.4 million of unrecognized compensation expense related to RSUs, which is expected to be recognized over a weighted-average period of 3.09 years. The aggregate intrinsic values based on the $62.86 closing price of our common stock as reported on the Nasdaq Global Market on December 31, 2019 of unvested RSUs is $109.5 million and RSUs expected to vest is $89.8 million as of December 31, 2019.

Subsequent to December 31, 2019, we granted 188,422 RSUs to employees, which have annual vesting periods ranging from one to four years. The unamortized stock-based compensation expense related to these RSUs is approximately $15.9 million.

Performance-based Restricted Stock Units

During 2018, we granted two separate tranches of performance-based RSUs ("2018 PSUs"), each to receive 437,500 shares of common stock, to employees. The vesting of the 875,000 2018 PSUs was contingent upon the completion of our IPO and includes other performance-based conditions. The performance condition in the first tranche was to be satisfied when we attained 70.0 million of FI monthly active users ("FI MAUs") within three years of the grant date. The performance condition in the second tranche was to be satisfied when we attained 85.0 million of average FI MAUs within five years of the grant date. FI MAUs is a performance metric defined within "Management's Discussion and Analysis of Financial Condition and Results of Operations." We recognize stock compensation for these 2018 PSUs based upon the expected timing of the achievement of these FI MAU targets. During 2018, 25,000 of the 2018 PSUs were forfeited prior to the FI MAU targets being reached. During 2018, both average FI MAU targets were reached, resulting in the vesting of both tranches of the 2018 PSUs and the issuance of 850,000 shares of our common stock to fully settle the 2018 PSUs. During 2018, we recognized $18.6 million of stock-based compensation expense related to these awards.

During 2019, we granted 1,252,500 performance-based RSUs (“2019 PSUs”). The 2019 PSUs are composed of four equal tranches, each of which have an independent performance-based vesting condition. The vesting criteria for the four tranches are as follows:


•	a minimum growth rate in adjusted contribution over a trailing 12-month period,


•	a minimum number of advertisers that are billed above a specified amount over a trailing 12-month period,


•	a minimum cumulative adjusted EBITDA target over a trailing 12-month period, and


•	a minimum trailing 30-day average closing price of our common stock.

The vesting conditions of each of the four tranches must be achieved within four years of the grant date. Upon a vesting event, 50% of the related tranche vests immediately, 25% of the related tranche vests six months after achievement date and 25% of the related tranche vests 12 months after the achievement date. Adjusted EBITDA and adjusted contribution are performance metrics defined within "Management's Discussion and Analysis of Financial Condition and Results of Operations." During 2019, the Compensation Committee of our Board of Directors certified that the targets for both the average closing price of our common stock and adjusted EBITDA were achieved resulting in the immediate vesting of 50% of each related PSU tranche.

Restricted Securities Units

During 2016, we granted $1.0 million of restricted securities units to certain executives in lieu of cash bonuses. Upon issuance, the restricted securities units were indexed to the convertible promissory notes. As a result of the Series G Stock financing, the restricted securities units became indexed to our Series G’ Stock upon conversion of the convertible promissory notes. Upon the consummation of our IPO in February 2018, the restricted securities units became indexed to our common stock.

Vesting requirements included both a service-based condition and a performance-based condition. The service-based condition required each recipient to remain employed until the earlier of i) the date 6 months from the restricted securities unit grant date, ii) the date of a qualified liquidity event, or iii) date of termination without cause. The performance-based condition required a sale of the Company or IPO event within a fixed period of time not more than 5 years from the restricted securities units grant date. The restricted securities units were considered liability classified awards, but due to the performance condition relating to sale of the Company or IPO, no compensation cost was recognized until one of these events occurred. These units vested upon the consummation of our IPO in February 2018, resulting in a non-cash expense of $0.5 million, and were settled upon the delivery of 37,406 shares of our common stock in August 2018.

Employee Stock Purchase Plan

Our board of directors has adopted and our stockholders have approved our 2018 Employee Stock Purchase Plan ("2018 ESPP"). Our 2018 ESPP became effective on February 8, 2018, the date our registration statement in connection with our IPO was declared effective and enables eligible employees to purchase shares of our common stock at a discount. Purchases will be accomplished through participation in discrete offering periods. On each purchase date, eligible employees will purchase our common stock at a price per share equal to 85% of the lesser of the fair market value of our common stock on the first trading day of the offering period or the date of purchase. During 2018 and 2019, a total of 177,238 and 154,601 shares of common stock were purchased by employees under the 2018 ESPP, respectively.

As of December 31, 2019, 267,823 shares of common stock were reserved for issuance pursuant to our 2018 ESPP. Additionally, the number of shares of our common stock reserved for issuance under our 2018 ESPP will automatically increase on January 1 of each year, beginning on January 1, 2019 and continuing through and including January 1, 2026, by the lesser of (i) 1% of the total number of shares of our common stock outstanding on December 31 of the preceding calendar year, (ii) 500,000 shares of our common stock or (iii) such lesser number of shares of common stock as determined by our board of directors. Accordingly, the number of shares of our common stock reserved for issuance under our 2018 ESPP increased by 265,470 shares on January 1, 2020. Shares subject to purchase rights granted under our 2018 ESPP that terminate without having been issued in full will not reduce the number of shares available for issuance under our 2018 ESPP.

INCOME TAXES

12 Months Ended

Dec. 31, 2019

Income Tax Disclosure [Abstract]

INCOME TAXES

Domestic and foreign components of loss before income taxes are as follows (in thousands):



	Year Ended December 31,
	2017			2018			2019
Domestic	$	(16,711	)	$	(48,897	)	$	(13,464	)
Foreign	(2,930		)	(4,145		)	(3,680		)
Loss before income taxes	$	(19,641	)	$	(53,042	)	$	(17,144	)

The significant components of income tax (expense) benefit are as follows (in thousands):



	Year Ended December 31,
	2017			2018			2019
Current:
Federal	$	—		$	—		$	—
State	—			—			—
Foreign ⁽¹⁾	—			—			—
Total current	—			—			—
Deferred:
Federal	(28,331		)	6,896			1,326
State	2,345			1,264			622
Foreign	85			916			222
Change in uncertain tax positions	(120		)	(105		)	598
Change in valuation allowance	26,021			(8,971		)	(2,768		)
Total deferred	—			—			—
Income tax benefit	$	—		$	—		$	—


(1)	The current income tax (expense) for the year ended December 31, 2019 excludes Indian income tax expense of less than $0.1 million.

The following table summarizes the significant differences between the U.S. federal statutory tax rate and our effective tax rate:



	Year Ended December 31,
	2017		2018		2019
Tax benefit at federal statutory rate	34.00	%	21.00	%	21.00	%
State income taxes, net of federal benefit	1.82	%	1.91	%	—	%
Change in federal and state statutory rate	(156.32	)%	0.03	%	0.34	%
Foreign rate differential	(1.04	)%	(0.06	)%	(0.20	)%
Other adjustments	(10.93	)%	(5.97	)%	(5.18	)%
Valuation allowance	132.47	%	(16.91	)%	(16.18	)%
Income tax benefit	—	%	—	%	(0.22	)%

The significant components of deferred income taxes are as follows (in thousands):



	December 31,
	2018			2019
Net operating loss carry-forwards	$	60,718		$	64,348
Allowance for doubtful accounts	26			28
Depreciation and amortization	(856		)	(1,321		)
Stock-based compensation	1,968			2,727
Deferred costs	1,334			2,275
IRC Section 163(j) interest expense limitation	737			436
Other tax credit carry-forward	3,071			1,419
Other temporary differences	465			319
Valuation allowance	(67,463		)	(70,231		)
Net long-term deferred tax liability	$	—		$	—

On December 22, 2017, the Tax Cuts and Jobs Act of 2017 (“Tax Act”) was signed into law making significant changes to the IRC. Changes include, but are not limited to, a corporate tax rate decrease to 21% effective for tax years beginning after December 31, 2017. This change in tax rate resulted in a reduction in our net U.S. deferred tax assets, which was fully offset by a reduction in our valuation allowance. The other provisions of the Tax Act, including the one-time transition tax on the mandatory deemed repatriation of cumulative foreign earnings, did not have a material impact on our financial statements as of December 31, 2019.

We have generated historical net losses and recorded a full valuation allowance against our net deferred tax assets. We expect to maintain a full valuation allowance in the near term. Realization of any of our net deferred tax assets depends upon future earnings, the timing and amount of which are uncertain.

The following table presents changes in our valuation allowance (in thousands):



	Year Ended December 31,
	2017			2018			2019
Beginning balance	$	(84,483	)	$	(58,649	)	$	(67,463	)
Allowance for domestic and foreign net operating loss carry-forwards	(6,509		)	(9,863		)	(3,598		)
Rate change on domestic net operating loss carry-forwards	30,705			(17		)	(32		)
Change in foreign currency	(187		)	157			—
Other changes	1,825			909			862
Ending balance	$	(58,649	)	$	(67,463	)	$	(70,231	)

As of December 31, 2018 and 2019 we have $249.8 million and $266.8 million, respectively, of gross U.S. federal net operating loss carry forwards that will begin to expire in the 2028 tax year. Additionally, we have $90.5 million and $98.4 million of gross state net operating loss carry-forwards as of December 31, 2018 and 2019, respectively that will also begin to expire in the 2028 tax year.

Ownership changes, as defined by IRC Section 382, may limit the amount of net operating losses that a company may utilize to offset future taxable income and taxes payable. Pursuant to IRC Section 382, an ownership change occurs when the stock ownership of 5% stockholders increases by more than 50% over a testing period of three years. We have experienced ownership changes in the past, and it is possible that we have undergone ownership changes subsequent to December 5, 2018, the date of our most recent evaluation, or that we may undergo such a change in the future. Any such ownership change may limit our ability to utilize net operating losses.

Our results during 2017, 2018 and 2019 reflect state tax credits related to hiring and research activities that are utilized through the reduction of state payroll tax withholdings totaling $0.8 million, $0.7 million and $1.3 million, respectively.

As of December 31, 2018 and 2019, Cardlytics UK had gross net operating losses of $13.9 million and $12.1 million, respectively. Foreign net operating loss carry-forwards expire according to the rules of each country. In the U.K., there is an indefinite carry-forward period. As of December 31, 2019, Cardlytics UK held cash and cash equivalents of $4.8 million. While our investment in Cardlytics UK is not considered to be permanently invested, we do not plan to repatriate these funds. Further, although the tax basis of our investment in Cardlytics UK exceeds its book basis, we have not recorded a deferred tax asset since we do not believe that a reversal of this temporary difference will occur in the foreseeable future.

The following table summarizes the activity related to our gross unrecognized tax benefits that would affect our effective tax rate, if recognized (in thousands):



	Year Ended December 31,
	2017		2018		2019
Beginning balance	$	558	$	678	$	783
Increase related to current year tax position	120		105		(598		)
Ending balance	$	678	$	783	$	185

All such positions, if recognized, would impact our effective tax rate. We do not currently anticipate any of our positions to change significantly in the next 12 months. Our tax filings from inception remain subject to income tax examinations.

REDEEMABLE CONVERTIBLE PREFERRED STOCK

12 Months Ended

Dec. 31, 2019

Temporary Equity Disclosure [Abstract]

REDEEMABLE CONVERTIBLE PREFERRED STOCK

Upon the consummation of our IPO, all of the outstanding shares of redeemable convertible preferred stock were automatically converted into shares of common stock. Refer to Note 1—Nature of Operations for additional information regarding our IPO.

A summary of the change in carrying amount of the outstanding redeemable convertible preferred stock is as follows (in thousands):



	Series G’ Stock					Series G Stock
	Shares		Amount			Shares		Amount
Balance — December 31, 2017	1,296		$	44,672		346		$	5,110
Conversion of preferred stock to common stock	(1,296	)	(44,672		)	(346	)	(5,218		)
Accretion of redeemable convertible preferred stock	—		—			—		108
Balance — December 31, 2018	—		—			—		—



	Series F/F-R Stock					Series E/E-R Stock					Series D/D-R Stock
	Shares		Amount			Shares		Amount			Shares		Amount
Balance — December 31, 2016	1,199		$	57,958		795		$	29,963		1,396		$	32,642
Accretion of redeemable convertible preferred stock	—		491			—		9			—		86
Balance — December 31, 2017	1,199		$	58,449		795		$	29,972		1,396		$	32,728
Accretion of redeemable convertible preferred stock	—		38			—		1			—		7
Conversion of preferred stock to common stock	(1,199	)	(58,487		)	(795	)	(29,973		)	(1,396	)	(32,735		)
Balance — December 31, 2018	—		$	—		—		$	—		—		$	—



	Series C/C-R Stock					Series B/B-R Stock					Series A/A-R Stock
	Shares		Amount			Shares		Amount			Shares		Amount
Balance — December 31, 2016	1,508		$	18,323		2,247		$	5,286		1,857		$	1,850
Accretion of redeemable convertible preferred stock	—		43			—		2			—		2
Balance — December 31, 2017	1,508		$	18,366		2,247		$	5,288		1,857		$	1,852
Accretion of redeemable convertible preferred stock	—		3			—		—			—		—
Conversion of preferred stock to common stock	(1,508	)	(18,369		)	(2,247	)	(5,288		)	(1,857	)	(1,852		)
Balance — December 31, 2018	—		$	—		—		$	—		—		$	—

During 2016, we issued convertible promissory notes to our founders and the existing holders of our redeemable convertible preferred stock. Shares of redeemable convertible preferred stock held by investors that participated in the financing were exchanged for shares of replacement preferred stock. Replacement shares were issued for 1,856,998 shares of Series A Stock, 2,246,744 shares of Series B Stock, 1,507,906 shares of Series C Stock, 1,395,936 shares of Series D Stock, 795,027 shares of Series E Stock and 1,198,637 shares of Series F Stock. These replacement shares have rights and preferences equal to their corresponding original series and are designated as Series A-R Stock, Series B-R Stock, Series C-R Stock, Series D-R Stock, Series E-R Stock and Series F-R Stock. Shares of redeemable convertible preferred stock held by investors that did not participate in the financing were converted to common stock and consisted of 12,375 shares of Series A Stock, 2,121 shares of Series B Stock and 397,515 shares of Series E Stock.

In February 2017, we amended and restated our certificate of incorporation reducing the authorized number of shares of our redeemable convertible preferred stock to 82,683,212 and canceled Series A Stock, Series B Stock, Series C Stock, Series D Stock, Series E Stock and Series F Stock. Pursuant to our convertible promissory note financing, these series of preferred stock were either exchanged for shares of replacement preferred stock with rights and preferences equal to their corresponding original series or converted to common stock.

Series G Stock Financing

In May 2017, we amended and restated our certificate of incorporation and increased the authorized number of shares of our common stock to 83,000,000 and increased the authorized number of shares of our redeemable convertible preferred stock to 96,131,002. In May 2017, we issued and sold, for aggregate consideration of $11.9 million, an aggregate of 346,334 shares of Series G redeemable convertible preferred stock, par value $0.0001 per share with a stated price of $34.4758 per share (“Series G Stock”), and warrants to purchase shares of our common stock. Issuance costs incurred in connection with the sale of Series G Stock totaled $0.1 million.

Conversion of Convertible Promissory Notes into Series G’ Stock

In connection with the Series G Stock financing in May 2017, the Existing Stockholder Notes and the Outstanding Obligation Note converted into 1,295,746 shares of Series G’ redeemable convertible preferred stock, par value $0.0001 per share (“Series G’ Stock”), at a price per share of $27.58. The Series G’ Stock carried a stated dividend of $2.758 per annum, payable quarterly when, as, and if declared by our board of directors. These dividends were noncumulative in nature. The Series G’ Stock was entitled to certain anti-dilution protections.

Common Stock Warrants Issued in Connection with the Series G Stock Financing

In connection with the Series G Stock financing, we issued warrants to purchase an aggregate number of shares of common stock equal to the product obtained by multiplying 346,334 by a fraction, the numerator of which is the difference between $68.9516 and the volume weighted average closing price of our common stock over the 30 trading days (or such lesser number of days as our common stock has been traded on the Nasdaq Global Market) prior to the date on which such warrants vest and become exercisable and the denominator of which is such volume weighted average closing price, which warrants vested and became exercisable on August 8, 2018, which was 180 days following the date of our IPO, at an exercise price of $0.0004 per share. In August 2018, we issued warrants to purchase 792,434 shares of common stock at an exercise price of $0.0004 per share to the cash investors of our Series G financing, pursuant to our Series G stock purchase agreement. The warrants had a valuation of $15.3 million upon issuance and were immediately exercised. Refer to Note 11—Fair Value Measurements for additional information regarding the valuation of the warrants issued in connection with the Series G Stock financing.

Beneficial Conversion Feature

The aggregate proceeds of $11.9 million from the Series G Stock financing were first allocated to the warrants to purchase shares of our common stock, which qualify as liabilities under ASC 480 and are recorded at fair value, with the residual value of $4.5 million allocated to our Series G Stock. As a result of this allocation, Series G Stock was determined to contain a beneficial conversion feature with an intrinsic value of $6.1 million. The amount assigned to the beneficial conversion feature was limited to the $4.5 million residual value allocated to Series G Stock and is classified as a component of additional paid-in capital. During 2017, we recorded a deemed dividend of $4.5 million related to the beneficial conversion feature, which is reflected below net loss to arrive at net loss available to common stockholders.

Redemption

At any time on or after May 4, 2022, upon written request of the holders of not less than 66 2/3% of the shares of redeemable convertible preferred stock then-outstanding, voting together as a single class on an as-converted to common stock basis, we were required to redeem all outstanding shares of redeemable convertible preferred stock in eight quarterly installments. The Series A-R Stock, Series B-R Stock, Series C-R Stock, Series D-R Stock, Series E-R Stock, Series F-R Stock, Series G Stock and Series G’ Stock were redeemable at prices equal to $1.00, $2.3567, $12.2686, $23.64, $37.7344, $58.40, $34.4758 and $34.4758 per share, plus any declared or accumulated but unpaid dividends, respectively.

To the extent that we had insufficient funds to redeem all outstanding shares of redeemable convertible preferred stock, we were required to first redeem shares of Series G Stock and Series G’ Stock, then shares of Series F/F-R Stock, then shares of Series E/E-R Stock, then shares of Series D/D-R Stock, then shares of Series C/C-R Stock and then shares of Series B/B-R Stock and Series A/A-R Stock pari passu, in each case on a pro rata basis among the holders thereof.

The redeemable convertible preferred stock carrying amount was increased by periodic accretions, using the interest method, so that the carrying amount would equal the redemption amount at May 4, 2022. Accretion was recorded through a charge against additional paid-in capital.

Liquidation

Upon us (i) selling or otherwise disposing of all or substantially all of our property or business or merging with or into or consolidation with any other corporation, limited liability company or other entity, (ii) a majority of the voting power of our outstanding capital stock being transferred or disposed of as a result of a transaction or series of related transactions that are not issuances of capital stock by us primarily for the purposes of raising equity capital or (iii) any dissolution or winding-up of our business, the holders of Series A-R Stock, Series B-R Stock, Series C-R Stock, Series D-R Stock, Series E-R Stock, Series F-R Stock, Series G Stock and Series G’ Stock were entitled to receive payments in amounts per share equaling $1.00, $2.3567, $21.4701, $23.64, $37.7344, $58.40, $68.9516, and $34.4758, plus any declared but unpaid dividends, respectively. Holders of Series G Stock and Series G’ Stock are pari passu and were to be paid prior, and in preference to, any distribution of assets to the holders of all other classes of capital stock. Holders of Series F-R Stock were to be paid prior, and in preference to, any distribution of assets to the holders of Series E-R Stock, Series D-R Stock, Series C-R Stock, Series B-R Stock and Series A-R Stock. Holders of Series E-R Stock were to be paid prior, and in preference to, any distribution of assets to the holders of Series D-R Stock, Series C-R Stock, Series B-R Stock and Series A-R Stock. Holders of Series D-R Stock were to be paid prior, and in preference to, any distribution of assets to the holders of Series C-R Stock, Series B-R Stock and Series A-R Stock. Holders of Series C-R Stock were to be paid prior, and in preference to, any distribution of assets to the holders of Series B-R Stock and Series A-R Stock. Holders of Series A-R Stock and Series B-R Stock are pari passu and were to be paid prior, and in preference to, any distribution of assets to the holders of common stock.

Upon completion of the distributions detailed above, any remaining assets were to be distributed to the holders of common stock, Series A-R Stock, Series B-R Stock, Series C-R Stock, Series D-R Stock, Series E-R Stock, Series F-R Stock, Series G Stock and Series G’ Stock; such participation in the distribution of remaining assets would cease, however, when the amount that the holders of Series A-R Stock, Series B-R Stock, Series C-R Stock, Series D-R Stock, Series E-R Stock, Series F-R Stock, Series G Stock and Series G’ Stock were entitled to receive upon liquidation equals $2.00 per share, $4.7134 per share, $36.8058 per share, $70.92 per share, $113.2032 per share, $175.20 per share, $103.4274 per share and $103.4274 per share, respectively, plus any declared but unpaid dividends thereon.

If, however, as a result of a conversion from redeemable convertible preferred stock to common stock, a holder would receive, in the aggregate, an amount greater than the amount that would be distributed to such holder if such holder did not convert such series of redeemable convertible preferred stock into shares of common stock, such holder would have been deemed to have converted such holder’s shares of redeemable convertible preferred stock into shares of common stock for the purposes of determining the amount that such holder is entitled to receive upon liquidation and would not have been entitled to any distribution that would have otherwise been made to the holders of redeemable convertible preferred stock detailed above.

Dividends

No dividends have been declared or paid as of December 31, 2019.

Conversion

The holders of our redeemable convertible preferred stock also had the right, at any time, to convert any or all of their shares into such number of shares of common stock as is determined by dividing $1.00 in the case of Series A-R Stock, $2.3567 in the case of the Series B-R Stock, $12.2686 in the case of Series C-R Stock, $23.64 in the case of Series D-R Stock, $37.7344 in the case of Series E-R Stock, $50.0568 in the case of Series F-R Stock, and $34.4758 in the case of Series G Stock and Series G’ Stock by the applicable conversion price. The initial conversion price was $1.00 in the case of Series A-R Stock, $2.3567 in the case of the Series B-R Stock, $2.3567 in the case of Series C-R Stock, $23.64 in the case of Series D-R Stock, $37.7344 in the case of Series E-R Stock, $50.0568 in the case of Series F-R and $34.4758 in the case of Series G Stock and Series G’ Stock. If, at any time following the initial issuance of shares of Series G Stock, we had issued any additional shares of capital stock without consideration or for a consideration per share less than the then-effective conversion price for our redeemable convertible preferred stock, the conversion price for all series of outstanding redeemable convertible preferred stock would have been subject to adjustment.

COMMON STOCK WARRANTS

12 Months Ended

Dec. 31, 2019

Other Liabilities Disclosure [Abstract]

COMMON STOCK WARRANTS

We have granted warrants to purchase shares of our common stock to certain FI partners that include both time-based and performance-based vesting conditions. These warrants are accounted for under ASC Topic 505-50, Equity-Based Payments to Non-Employees. Since the performance conditions contained in these warrants are directly related to revenue-producing activities, we incur non-cash expense in FI Share and other third-party costs on our consolidated statements of operations based on the vesting-date fair value of our common stock underlying these warrants.

A summary of common stock warrant activity, exclusive of the common stock warrants issued in connection with our Series G financing is as follows (in thousands, except per share amounts):



	Shares		Weighted-average exercise price per share
Warrants Outstanding - December 31, 2016	583		$	7.52
Granted	17		27.68
Warrants Outstanding - December 31, 2017	600		8.11
Granted⁽¹⁾	644		23.64
Exercised	(349	)	4.69
Redeemable convertible preferred stock warrants converted to common stock warrants	110		12.16
Forfeited/canceled	(138	)	5.85
Warrants Outstanding - December 31, 2018	867		21.89
Exercised	(821	)	21.89
Forfeited/canceled	(34	)	21.29
Warrants Outstanding - December 31, 2019	12		$	23.64


(1)	Performance-based warrants to purchase 644,365 shares of our Series E Stock, which were converted to common stock warrants, vested upon the completion of our IPO in February 2018. These warrants are not included within this table in periods prior to their vesting.

In June 2017, we issued our lender additional warrants to purchase 17,500 shares of common stock at a price of $27.68 per share.

During 2017, warrants to purchase shares of redeemable convertible preferred stock held by parties that did not participate in the Existing Stockholder Note financing were converted to common stock warrants. As a result, fully vested warrants to purchase 12,500 shares of our Series A Stock at an exercise price of $1.00 per share, fully vested warrants to purchase 25,000 shares of our Series B Stock at an exercise price of $2.36 per share and unvested performance-based warrants to purchase 644,365 shares of our Series E Stock at an exercise price of $23.64 per share were converted to common stock warrants. The performance-based warrants to purchase 644,365 shares of our Series E Stock, which were converted to common stock warrants, vested upon the consummation of our IPO in February 2018 as discussed in Note 12—Related Parties. The conversion date fair value of the Series A Stock warrants and Series B Stock warrants, which were converted to common stock warrants, was reclassified from redeemable convertible preferred stock warrant liability to additional paid-in capital. See Note 11—Fair Value Measurements for more information.

All common stock warrants outstanding at December 31, 2019 were net exercised in January 2020.

FAIR VALUE MEASUREMENTS

12 Months Ended

Dec. 31, 2019

Fair Value Disclosures [Abstract]

FAIR VALUE MEASURMENTS

FAIR VALUE MEASUREMENTS

Financial assets and liabilities are classified in their entirety based on the lowest level of input that is significant to the fair value measurement. The following table summarizes our liabilities measured at fair value on a recurring basis by level within the fair value hierarchy (in thousands):



	December 31, 2017
	Level 1		Level 2		Level 3		Total
Liabilities:
Preferred stock warrants⁽¹⁾	$	—	$	—	$	2,285	$	2,285
Common stock warrants⁽¹⁾	—		—		7,945		7,945
Total liabilities	$	—	$	—	$	10,230	$	10,230


(1)	Warrant liabilities were zero as of December 31, 2018 and 2019.

Instruments Recorded at Fair Value Using Level 3 Inputs

Our redeemable convertible preferred stock warrants, common stock warrants issued in connection with the Series G Stock financing and our convertible promissory notes are measured and recorded at fair value on a recurring basis using Level 3 inputs. The table below provides a roll forward of the changes in fair value of Level 3 financial instruments (in thousands):



	Preferred Stock Warrants		Common Stock Warrants		Convertible Promissory Notes
Balance at December 31, 2016	$	2,197	$	—	$	72,332
Fair value of convertible promissory notes at issuance	—		—		(44,672		)
Conversion of convertible promissory notes to Series G’ preferred stock	—		—		(24,392		)
Accrued interest on convertible promissory notes	—		—		1,701
Issuance of common stock warrants	—		7,452		—
Changes in fair value	88		493		(4,969		)
Balance at December 31, 2017	$	2,285	$	7,945	$	—



	Preferred Stock Warrants			Common Stock Warrants			Convertible Promissory Notes
Balance at December 31, 2017	$	2,285		$	7,945		$	—
Conversion of convertible promissory notes to common stock	(1,736		)	—			—
Issuance of common stock warrants	(549		)	7,309			—
Changes in fair value	—			(15,254		)	—
Balance at December 31, 2018	$	—		$	—		$	—

In valuing our instruments recorded at fair value using Level 3 inputs, our board of directors determined the equity value of our business generally using a combination of the income approach and the market approach valuation methods.

The income approach estimates value based on the expectation of future cash flows that a company will generate, such as cash earnings, cost savings, tax deductions and the proceeds from disposition. These future cash flows are discounted to their present values using a discount rate derived based on an analysis of the cost of capital of comparable publicly traded companies in similar lines of business, as of each valuation date, and is adjusted to reflect the risks inherent in our cash flows.

The market approach estimates the fair value of a company by applying market multiples of comparable publicly traded companies in a similar line of business. The market multiples are based on relevant metrics implied by the price that investors have paid for the equity of publicly traded companies. Given our significant focus on investing in and growing our business, we primarily utilized the forward-looking revenue multiple when performing valuation assessments under the market approach and considered both trading and transaction multiples. When considering which companies to include as our comparable industry peer companies, we focused on U.S.-based publicly traded companies that were broadly comparable to us based on consideration of industry, market and line of business. From the comparable companies, a representative market value multiple was determined and applied to our operating results to estimate the value of our company. The market value multiple was determined based on consideration of multiples of revenue to each of the comparable companies’ historical and forecasted revenue. In addition, the market approach considers IPO and merger and acquisition transactions involving companies similar to the company’s business being valued. Multiples of revenue are calculated for these transactions and then applied to the business being valued, after reduction by an appropriate discount.

Once an equity value was determined, beginning January 1, 2017, we utilized probability-weighted expected return method (“PWERM”) to allocate the overall value of equity to the various share classes. The PWERM relies on a forward-looking analysis to predict the possible future value of a company. Under this method, discrete future outcomes, including an IPO and non-IPO scenarios, are weighted based on the estimated the probability of each scenario. The PWERM is used when discrete future outcomes can be predicted with reasonable certainty based on a probability distribution. We relied on the PWERM to allocate the value of equity under a liquidity scenario. The projected equity value relied upon in the PWERM scenario was based on (i) guideline IPO transactions involving companies that were considered broadly comparable to us and (ii) our expectation of the pre-money valuation that we needed to achieve to consider an IPO as a viable exit strategy.

The following table summarizes key assumptions used in the PWERM for estimating the fair value of our redeemable convertible preferred stock warrant liability:



	Year Ended December 31,
	2017
Cost of debt applicable to convertible promissory notes	—%
Cost of equity applicable to convertible promissory notes	—%
Weighted-average cost of capital applicable to preferred stock warrants	21%
Discount for lack of marketability	7% to 13%
Volatility	55%
Risk-free interest rate	1.2% to 1.4%

Preferred Stock Warrants

Upon the consummation of our IPO, all of the outstanding warrants to purchase shares of redeemable convertible preferred stock were automatically converted into warrants to purchase shares of common stock. Refer to Note 9—Redeemable Convertible Preferred Stock for additional information regarding our IPO.

A summary of our preferred stock warrants is as follows (in thousands, except per share amounts):



					December 31,
Preferred Series	Grant date	Expiration date	Exercise price		2017	2018	2019
Series B-R	2/26/2010	2/25/2020	$	2.36	59	—	—
Series D-R	9/21/2012	9/20/2022	$	23.64	38	—	—
Series D-R	9/21/2012	9/20/2022	$	23.64	13	—	—
Total preferred stock warrants					110	—	—

The fair value of the warrants to purchase Series B-R Stock and Series D-R Stock decreased from $26.80 per share and $13.63 per share on December 31, 2017 to $20.18 per share and $10.57 per share on February 8, 2018, respectively, the date at which they converted to warrants to purchase shares of our common stock and were reclassified to additional paid-in capital on our consolidated balance sheet. The decrease in the fair value of the warrants to purchase Series B-R Stock and Series D-R Stock primarily resulted from the timing of future potential liquidity events, changes to our forecasted financial results and changes in the valuation of comparable companies.

Common Stock Warrants

In June 2017, we issued our lender additional warrants to purchase 17,500 shares of common stock at a price of $27.68 per share. The fair value of the warrants issued in June 2017 were calculated to be $0.3 million. We determined the grant date fair value of these common warrants using the Black-Scholes option pricing model, which is affected by the estimated fair value of our common stock as well as the following significant inputs:



	Common stock warrants (issued June 2017)
Weighted-average grant date fair value	$19.04
Significant inputs:
Value of common stock	$30.08
Expected term	10 years
Volatility	50%
Risk-free interest rate	2.2%
Dividend yield	—%

Common Stock Warrants Issued in Connection with the Series G Stock Financing

To determine the fair value of our common stock warrant liability issued in connection with our Series G Stock financing, we utilized a Monte Carlo simulation, which allows for the modeling of complex securities and evaluates many possible outcomes to forecast the stock price of the company post-IPO. As part of the valuation, we considered various scenarios related to the pricing, timing and probability of an IPO. We applied an annual equity volatility of 59% and a discount for lack of marketability of 11% to arrive at a valuation of $7.5 million on the issuance date.

Subsequent to our IPO, the fair value of the common stock warrant liability was estimated based on the fair market value of our common stock at each reporting period, discounted from the date of settlement. In August 2018, we issued warrants to purchase 792,434 shares of common stock at an exercise price of $0.0004 per share to the cash investors of our Series G financing, pursuant to our Series G stock purchase agreement. The warrants had a valuation of $15.3 million upon issuance and were subsequently exercised, resulting in the issuance of 792,434 shares of our common stock. As a result of change in fair value of the common stock warrant liability, we recognized non-cash losses of $0.5 million and $7.3 million in 2017 and 2018, respectively.

Convertible Promissory Notes

Refer to Note 9—Redeemable Convertible Preferred Stock for additional information of the Series G Stock financing and the transactions that resulted in the conversion of the convertible promissory notes into shares of our Series G’ Stock.

The redemption features included in the terms of the convertible promissory notes were determined to be derivative liabilities due to a significant discount within the redemption features for the note holders. Embedded derivatives that are not clearly and closely related to the host contract are required to be bifurcated and recorded at fair value unless the fair value option is elected on the host contract. Under the fair value option, bifurcation of the embedded derivative is not necessary as all related gains (losses) on the host contract and derivative will be reflected in the consolidated statements of operations. We elected the fair value option for the Existing Stockholder Notes and Aimia Notes, therefore direct costs and fees associated with the issuance were recognized in earnings as incurred and were not deferred.

To determine the fair value of our convertible promissory notes, we utilized key assumptions from the PWERM, as shown above. Under this method, we considered the redemption features of the convertible promissory notes, as described in Note 6—Debt for additional information, to determine the fair value under discrete future outcomes, including IPO and non-IPO scenarios. Under certain non-IPO scenarios, holders of the convertible promissory notes were due to receive two times preference on the outstanding principal amount. We weighted the fair values based on the estimated probability of each scenario to determine the overall fair value of the convertible promissory notes as of the balance sheet date.

Performance-based Warrants Issued to FIS

In May 2013, we granted 10-year performance-based warrants to purchase up to 644,365 shares of Series E Stock at an exercise price of $23.64 per share. Since FIS did not participate in the convertible promissory note financing, their warrants to purchase preferred stock were converted to warrants to purchase common stock. The warrants vested upon the completion of our IPO in February 2018 resulting in a non-cash expense of $2.5 million. We determined the fair value of these common warrants on the date of IPO using the Black-Scholes option pricing model, which is affected by the fair value of our common stock as well as the following significant inputs:



	February 8, 2018
Weighted-average grant date fair value	$3.91
Significant inputs:
Value of common stock	$13.00
Expected term	5.3 years
Volatility	50%
Risk-free interest rate	2.0%
Dividend yield	—%

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

+ References + Details

RELATED PARTIES

12 Months Ended

Dec. 31, 2019

RELATED PARTIES

Series G / Series G’

In May 2017, we issued and sold, for aggregate consideration of $11.9 million, an aggregate of 346,334 shares of our Series G Stock and warrants to purchase shares of our common stock. In connection with the issuance of our Series G Stock, the principal and accrued interest under convertible promissory notes converted into an aggregate of 1,295,746 shares of our Series G’ redeemable convertible preferred stock and 801,329 shares of our common stock. The following table summarizes the participation in the foregoing transactions by our directors, executive officers and holders of more than 5% of any class of our capital stock as of the date of such transactions (in thousands):



Related Party	Shares of Series G Preferred Stock	Shares of Series G’ Preferred Stock	Shares of Common Stock	Warrants to Purchase Common Stock
Entities affiliated with Aimia, Inc.⁽¹⁾	—	382	801	—
Entities affiliated with Polaris Venture Partners⁽²⁾	29	212	—	66
Canaan VIII L.P.⁽³⁾	54	260	—	123
Entities affiliated with Discovery Capital⁽⁴⁾	—	106	—	—
Scott D. Grimes	—	26	—	—
Lynne M. Laube	—	14	—	—
Entities affiliated with Mark A. Johnson⁽⁵⁾	35	15	—	80
John Klinck	6	—	—	13
David Adams	3	—	—	7


(1)	Consists of 159,207 shares of Series G’ redeemable convertible preferred stock issued to Aeroplan Holdings Europe Sàrl, 223,020 shares of Series G’ redeemable convertible preferred stock issued to Aimia EMEA Limited and 801,329 shares of common stock issued to Aimia EMEA Limited.

(2)

Consists of 27,988 shares of Series G redeemable convertible preferred stock purchased by Polaris Venture Partners V, L.P. (“PVP V”), 205,020 shares of Series G’ redeemable convertible preferred stock issued to PVP V, 64,038 warrants to purchase common stock issued to PVP V, 545 shares of Series G redeemable convertible preferred stock purchased by Polaris Venture Partners Entrepreneurs’ Fund V, L.L. (“PVP EF V”), 3,995 shares of Series G’ redeemable convertible preferred stock issued to PVP EF V, 1,247 warrants to purchase common stock issued to PVP EF V, 191 shares of Series G redeemable convertible preferred stock purchased by Polaris Venture Partners Founders’ Fund V, L.P. (“PVP FF V”), 1,404 shares of Series G’ redeemable convertible preferred stock issued to PVP FF V, 438 warrants to purchase common stock issued to PVP FF V, 280 shares of Series G redeemable convertible preferred stock purchased by Polaris Venture Partners Special Founders’ Fund V, L.P. (“PVP SFF V”), 2,050 shares of Series G’ redeemable convertible preferred stock issued to PVP SFF V and 641 warrants to purchase common stock issued to PVP SFF V. Polaris Venture Management Co. V, L.L.C. is a general partner of each of PVP V, PVP EF V, PVP FF V and PVP SFF V and may be deemed to have the sole voting and dispositive power over the shares held by PVP V, PVP EF V, PVP FF V and PVP SFF V. Bryce Youngren, a member of our board of directors, is a Managing Partner of Polaris Partners and may be deemed to share voting and dispositive power over the shares held by PVP V, PVP EF V, PVP FF V and PVP SFF V.


(3)	John V. Balen, a member of our board of directors, is a managing member of Canaan Partners VIII LLC, the general partner of Canaan VIII L.P. Mr. Balen does not have voting or investment power over any shares held directly by Canaan VIII L.P.


(4)	Consists of 95,272 shares of Series G’ redeemable convertible preferred stock issued to Discovery Opportunity Master Fund, Ltd. and 11,072 shares of Series G’ redeemable convertible preferred stock issued to Discovery Global Focus Master Fund, Ltd.

(5)

Consists of 15,045 shares of Series G’ redeemable convertible preferred stock issued to TTP Fund II, L.P., 29,005 shares of Series G redeemable convertible preferred stock purchased by TTV Ivy Holdings, LLC, 66,365 warrants to purchase common stock issued to TTV Ivy Holdings, LLC, 5,801 shares of Series G redeemable convertible preferred stock purchased by Mr. Johnson, and 13,273 warrants to purchase common stock issued to Mr. Johnson. TTV Capital is a provider of management services to TTP GP II, LLC, which is a general partner of TTP Fund II, L.P. TTV Capital is the manager of TTV Ivy Holdings Manager, LLC, which is the general partner of TTV Ivy Holdings, LLC. Mark A. Johnson, a member of our board of directors, is a member of each of TTP GP II, LLC and TTV Ivy Holdings Managers, LLC and holds the title of partner of TTV Capital, and may be deemed to share voting and dispositive power over the shares held by TTP Fund II L.P. and TTV Ivy Holdings, LLC.

Agreements with Fidelity Information Services, LLC

We are party to a reseller agreement with Fidelity Information Services LLC (“FIS”). Pursuant to the reseller agreement, FIS markets and sells our services to financial institutions that are current or potential customers of FIS in exchange for a revenue share percentage. We are also obligated to make milestone payments to FIS related to the integration and deployment of our solutions. Prior to our IPO, FIS was entitled to elect a member of our board of directors, who was Robert Legters until his resignation immediately prior to our IPO in February 2018.

In May 2013, FIS purchased 397,515 shares of our Series E Stock. We also granted 10-year performance-based warrants to purchase up to 644,365 shares of Series E Stock at an exercise price of $23.64 per share. The warrants were exercisable subject to the attainment of certain milestones related to the number of active accounts for which our solutions have been enabled with accelerated vesting upon an IPO. Since FIS did not participate in the convertible promissory note financing, their warrants to purchase preferred stock were converted to warrants to purchase common stock. The warrants vested upon the completion of our IPO in February 2018, resulting in a non-cash expense of $2.5 million based on the vesting-date fair value of our common stock underlying these warrants. Since the performance conditions were directly related to revenue-producing activities, we recognized this expense in FI Share and other third-party costs on our consolidated statement of operations. This expense is presented in other non-cash expenses on our consolidated statement of statement of cash flows. Refer to Note 11—Fair Value Measurements for additional information regarding the valuation of the performance-based warrants issued to FIS.

In September 2019, FIS exercised all of their warrants to purchase common stock, resulting in cash proceeds of $15.2 million and the issuance of 644,365 shares of our common stock.

COMMITMENTS AND CONTINGENCIES

12 Months Ended

Dec. 31, 2019

Commitments and Contingencies Disclosure [Abstract]

COMMITMENTS AND CONTINGENCIES

FI Implementation Costs

Agreements with certain FI partners require us to fund the development of specific enhancements, pay for certain implementation fees, or make milestone payments upon the deployment of our solution. Amounts paid to FI partners are included in deferred FI implementation costs on our consolidated balance sheets the earlier of when paid or earned and are amortized over the remaining term of the related contractual arrangements. Amortization is included in FI Share and other third-party costs on our consolidated statements of operations and is presented in amortization of deferred FI implementation costs on our consolidated statement of cash flows. Certain of these agreements provide for future reductions in FI Share due to the FI partner. These reductions in FI Share are recorded as a reduction to deferred implementation costs and also result in a cumulative adjustment to accumulated amortization. During 2018, development payments to a certain FI partner totaled $9.3 million which was partially offset by recoveries through FI Share payment reductions of $4.6 million in 2019.

The following table presents changes in deferred FI implementation costs (in thousands):



	December 31,
	2017			2018			2019
Beginning balance	$	8,451		$	13,625		$	15,877
Deferred costs	10,900			9,250			—
Recoveries through FI Share	(4,100		)	(5,380		)	(4,625		)
Amortization	(1,626		)	(1,618		)	(2,869		)
Ending balance	$	13,625		$	15,877		$	8,383

Payments to FI partners for enhancements not yet placed in service totaled $1.0 million as of December 31, 2019. Future amortization, based on the amounts earned as of December 31, 2019, exclusive of amounts expected to be recovered, is as follows (in thousands):



Years Ending December 31,	Amortization
2020	$	3,915
2021	3,509
Total	$	7,424

We have a minimum FI Share commitment with a certain FI partner totaling $10.0 million over a 12-month period following the completion of certain milestones, which were not met as of December 31, 2019. Any expected shortfall will be accrued during the 12-month period following the completion of the milestones.

Operating Leases

We lease property and equipment under non-cancelable operating lease agreements expiring on various dates through April 2026. For leases that contain rent escalation or rent concession provisions, we record the total rent expense during the lease term on a straight-line basis over the term of the lease. On our consolidated balance sheets, the current portion of deferred rent is included in accrued liabilities and the long-term portion is included within deferred liabilities. Rent expense during 2017, 2018 and 2019 totaled $3.0 million, $3.0 million and $3.0 million, respectively.

In August 2013, we entered into a lease of 130 months for our new corporate headquarters in Atlanta, Georgia. The facility was delivered to us in July 2014 and provides 76,880 square feet of office space. The lease contains a $3.8 million tenant improvement allowance that is included in deferred rent and amortized as a reduction to rent expense over the lease term. Minimum lease payments under the agreement total $16.0 million. The lease is secured by an irrevocable letter of credit issued by our lender, which totaled $0.5 million as of December 31, 2019.

In May 2019, we entered into a lease of 36 months for an office in Victoria, London to provide 5,000 square feet of office space. Minimum lease payments under the agreement total £3.8 million.

As of December 31, 2019, future minimum lease payments under non-cancellable operating leases are as follows (in thousands):



Years Ending December 31,	Minimum Lease Payments
2020	$	3,040
2021	2,759
2022	2,808
2023	1,847
2024	1,807
Thereafter	611
Total	$	12,872

Litigation

From time to time, we may become involved in legal actions arising in the ordinary course of business including, but not limited to, intellectual property infringement and collection matters. We make assumptions and estimates concerning the likelihood and amount of any potential loss relating to these matters using the latest information available. We record a liability for litigation if an unfavorable outcome is probable and the amount of loss or range of loss can be reasonably estimated. If an unfavorable outcome is probable and a reasonable estimate of the loss is a range, we accrue the best estimate within the range. If no amount within the range is a better estimate than any other amount, we accrue the minimum amount within the range. If an unfavorable outcome is probable but the amount of the loss cannot be reasonably estimated, we disclose the nature of the litigation and indicates that an estimate of the loss or range of loss cannot be made. If an unfavorable outcome is reasonably possible and the estimated loss is material, we disclose the nature and estimate of the possible loss of the litigation. We do not disclose information with respect to litigation where an unfavorable outcome is considered to be remote or where the estimated loss would not be material. Based on current expectations, such matters, both individually and in the aggregate, are not expected to have a material adverse effect on our liquidity, results of operations, business or financial condition.

EARNINGS PER SHARE

12 Months Ended

Dec. 31, 2019

Earnings Per Share [Abstract]

EARNINGS PER SHARE

Diluted net loss per share is the same as basic net loss per share for 2017, 2018 and 2019 because the effects of potentially dilutive items were anti-dilutive, given our net loss during these periods. The following securities have been excluded from the calculation of diluted weighted-average common shares outstanding because the effect is anti-dilutive (in thousands):



	December 31,
	2017	2018	2019
Redeemable convertible preferred stock	10,644	—	—
Common stock options	2,514	1,774	1,000
Common stock warrants	1,245	867	12
Common stock warrants issuable pursuant to Series G Stock financing	547	—	—
Redeemable convertible preferred stock warrants	110	—	—
Restricted stock units	—	381	1,741
Restricted securities units	37	—	—
Common stock issuable pursuant to the ESPP	—	36	7

SEGMENTS

12 Months Ended

Dec. 31, 2018

Segment Reporting [Abstract]

SEGMENTS

As of December 31, 2019, we have three operating segments: Cardlytics Direct in the U.S. and U.K. and Other Platform Solutions, as determined by the information that both our Chief Executive Officer and President and Chief Operating Officer, who we consider our chief operating decision makers, use to make strategic goals and operating decisions. Our Cardlytics Direct operating segments in the U.S. and U.K. represent our proprietary native bank advertising channels and are aggregated into one reportable segment given their similar economic characteristics, nature of service, types of customers and method of distribution.

Our Other Platform Solutions enabled marketers and marketing service providers to leverage the power of purchase intelligence outside the bank channel. We have shifted the substantial majority of our efforts and resources to support the growth of Cardlytics Direct. As a result, we no longer generate revenue from Other Platform Solutions and do not expect to generate revenue from Other Platform Solutions for the foreseeable future.

Revenue can be directly attributable to each segment. With the exception of a non-cash equity expense and the amortization of deferred FI implementation costs, FI Share is also directly attributable to each segment. Our chief operating decision makers allocate resources to, and evaluate the performance of, our operating segments based on revenue and adjusted contribution. The accounting policies of each of our reportable segments are the same as those described in the summary of significant accounting policies.

The following table provides information regarding our reportable segments (in thousands):



	Year Ended December 31,
	2017		2018		2019
Cardlytics Direct:
Adjusted contribution⁽²⁾	$	55,184	$	69,364	$	95,219
Plus: FI Share and other third-party costs ⁽¹⁾⁽²⁾	67,207		79,959		115,211
Revenue	$	122,391	$	149,323	$	210,430
Other Platform Solutions:
Adjusted contribution⁽²⁾	$	3,560	$	86	$	—
Plus: FI Share and other third-party costs ⁽¹⁾⁽²⁾	4,414		1,275		—
Revenue	$	7,974	$	1,361	$	—
Total:
Adjusted contribution⁽²⁾	$	58,744	$	69,450	$	95,219
Plus: FI Share and other third-party costs ⁽¹⁾⁽²⁾	71,621		81,234		115,211
Revenue	$	130,365	$	150,684	$	210,430


(1)	Adjusted FI Share and other third-party costs presented above represents GAAP FI Share and other third-party data costs less a non-cash equity expense included in FI Share and amortization of deferred FI implementation costs, which are detailed below in our reconciliation of GAAP loss before income taxes to adjusted contribution.


(2)	Adjusted contribution and FI Share and other third-party costs include the impact of a $0.8 million gain during 2018 related to the renewal of our agreement with an FI partner, which contains certain amendments that are retroactively applied as of January 1, 2018.

Adjusted Contribution

Adjusted contribution measures the degree by which revenue generated from our marketers exceeds the cost to obtain the purchase data and the digital advertising space from our FI partners. Adjusted contribution demonstrates how incremental marketing spend on our platform generates incremental amounts to support our sales and marketing, research and development, general and administration and other investments. Adjusted contribution is calculated by taking our total revenue less our FI Share and other third-party costs exclusive of a non-cash equity expense and amortization of deferred FI implementation costs, which are non-cash costs. Adjusted contribution does not take into account all costs associated with generating revenue from advertising campaigns, including sales and marketing expenses, research and development expenses, general and administrative expenses and other expenses, which we do not take into consideration when making decisions on how to manage our advertising campaigns. We have recast all historical disclosures of adjusted contribution for the periods presented.

The following table presents a reconciliation of loss before income taxes presented in accordance with GAAP to adjusted contribution (in thousands):



	Year Ended December 31,
	2017			2018			2019
Adjusted contribution⁽¹⁾⁽²⁾	$	58,744		$	69,450		$	95,219
Minus:
Non-cash equity expense included in FI Share⁽¹⁾	—			2,519			—
Amortization of deferred FI implementation costs⁽¹⁾	1,626			1,618			2,869
Delivery costs	7,012			10,632			12,893
Sales and marketing expense	31,927			41,878			43,828
Research and development expense	12,150			16,210			11,699
General and administration expense	20,100			34,228			36,720
Depreciation and amortization expense	3,028			3,282			4,535
Total non-operating expense (income)	2,542			12,125			(181		)
Loss before income taxes	$	(19,641	)	$	(53,042	)	$	(17,144	)


(1)	Non-cash equity expense included in FI Share and amortization of deferred FI implementation costs are excluded from FI Share and other third-party costs, which is shown above in our reconciliation of GAAP revenue to non-GAAP adjusted contribution.


(2)	Adjusted contribution includes the impact of a $0.8 million gain during 2018 related to the renewal of our agreement with an FI partner, which contains certain amendments that are retroactively applied as of January 1, 2018.

The following tables provide geographical information (in thousands):



	Year Ended December 31,
	2017		2018		2019
Revenue:
United States	$	113,509	$	131,563	$	186,864
United Kingdom	16,856		19,121		23,566
Total	$	130,365	$	150,684	$	210,430



	December 31,
	2018		2019
Property and equipment:
United States	$	9,794	$	12,052
United Kingdom	436		2,010
India	—		228
Total	$	10,230	$	14,290

Capital expenditures within the United Kingdom were less than $0.1 million and $2.0 million during 2018 and 2019, respectively.

Concentrations of Risk

Customers

Financial instruments that potentially subject us to concentrations of credit risk consist primarily of cash and cash equivalents and accounts receivable. Our cash and cash equivalents are held with three financial institutions, which we believe are of high credit quality. We believe that our accounts receivable credit risk exposure is limited as a result of being diversified among a large number of marketers segregated by both geography and industry. Historically, we have not experienced significant write-downs of our accounts receivable. No marketer represented a significant concentration of our accounts receivable as of December 31, 2018. One marketer represented 10% of our accounts receivable as of December 31, 2019. During 2019, one marketer accounted for 11% of our revenue. No marketer accounted for over 10% of revenue during 2017 or 2018.

FI Partners

Our business is substantially dependent on a limited number of FI partners. We require participation from our FI partners in Cardlytics Direct and access to their purchase data in order to offer our solutions to marketers and their agencies. We must have FI partners with a sufficient number of customers and levels of customer engagement to ensure that we have robust purchase data and marketing space to support a broad array of incentive programs for marketers. Our agreements with a substantial majority of our FI partners have terms of three to five years but are generally terminable by the FI partner on 90 days or less prior notice. If an FI partner terminates its agreement with us, we would lose that FI as a source of purchase data and digital banking customers.

During 2017, 2018 and 2019, Bank of America, National Association accounted for 63%, 64% and 36% of the total FI Share we paid to our FI partners, respectively. During 2018 and 2019, JPMorgan Chase Bank, National Association accounted for 6% and 42% of the total FI Share we paid to our FI partners, respectively. During 2017, an FI partner in the U.K. accounted for 12% of the total FI Share we paid to our FI partners. No other FI partners accounted for over 10% of FI Share during 2017, 2018 or 2019.

SIGNIFICANT ACCOUNTING POLICIES (Policies)

12 Months Ended

Dec. 31, 2019

Accounting Policies [Abstract]

Principles of Consolidation

The consolidated financial statements include the accounts of the Company and its wholly-owned subsidiaries. All intercompany transactions and balances have been eliminated in consolidation.

Use of Estimates

Foreign Currency

Revenue

FI Share and Other Third-Party Costs

We report our revenue on our consolidated statements of operations gross of FI Share. FI Share costs are included in FI Share and other third-party costs in our consolidated statements of operations, rather than as a reduction of revenue, because we and not our FI partners act as the principal in our arrangements with marketers. We are responsible for the fulfillment and acceptability of the services purchased by marketers. We also have latitude in establishing the price of our services, have discretion in supplier selection and earn variable amounts. FI partners only supply consumer purchase data and digital marketing space and generally have no involvement in the marketing campaigns or contractual relationship with marketers.

Contract Costs

Given the short-term nature of our marketing campaigns, all contract costs are expensed as incurred since the expected period of benefit is less than one year. Costs to fulfill a contract include immaterial costs to set up a campaign that we expense as incurred due to the short-term nature of our marketing campaigns

Revenue Recognition

We determine revenue recognition through the following steps:


•	identification of a contract with a customer,


•	identification of the performance obligation(s) in the contract,


•	determination of the transaction price,


•	allocation of the transaction price to the performance obligation(s) in the contract, and


•	recognition of revenue when or as the performance obligation(s) are satisfied.

We sell our solutions by entering into agreements directly with marketers or their marketing agencies, generally through the execution of insertion orders. The agreements state the terms of the arrangement, the negotiated fee, payment terms and the fixed period of time of the campaign. We consider a contract to exist when a campaign, which typically lasts 45 days, is published to an FI partner under the terms of an insertion order.

With respect to our Cardlytics Direct service, our performance obligation is to offer incentives to FIs' customers to make purchases from the marketer within a specified period. This performance obligation is a series that represents a stand ready obligation to provide a targeted campaign for the marketer to FIs' customers. Cardlytics Direct fees represent variable consideration that is resolved when FIs' customers make qualifying purchases during the marketing campaign term.

Subsequent to a qualifying purchase, the associated fees are generally not subject to refund or adjustment unless the fees from the marketing campaign exceed a contractual maximum (marketer budget). We have not constrained our revenue because adjustments have historically been immaterial and given the short duration of our marketing campaigns, any adjustments are recognized during the period of the marketing campaign. We recognize revenue for Cardlytics Direct fees over time using the right to invoice practical expedient because the amount billed is equal to the value delivered to marketers through qualified purchases by FIs' customers during that period.

Consumer Incentives

We report our revenue on our consolidated statements of operations net of Consumer Incentives. We do not provide the goods or services that are purchased by our FIs’ customers from the marketers to which the Consumer Incentives relate. Accordingly, the marketer is deemed to be the principal in the relationship with the customer and, therefore, the Consumer Incentive is deemed to be a reduction in the purchase price paid by the customer for the marketer’s goods or services. While we are responsible for remitting Consumer Incentives to our FI partners for further payment to their customers, we function solely as an agent of marketers in these arrangements.

We invoice marketers monthly based on the qualifying purchases of FIs' customers as reported by our FI partners during the month. Invoice payment terms, negotiated on a marketer-by-marketer basis, are typically between 30 to 60 days. However, for certain marketing agencies with sequential liability terms, payments are not due to us until such marketing agency has received payment from its marketer client. Accounts receivable is recorded at the amount of gross billings to marketers, net of allowances, for the fees and Consumer Incentives that we are responsible to collect. Our accrued liabilities also include the amount of Consumer Incentives due to FI partners. As a result, accounts receivable and accrued liabilities may appear large in relation to revenue, which is reported on a net basis. During 2017, 2018 and 2019, Consumer Incentives totaled $61.2 million, $68.3 million and $105.6 million, respectively.

FI Share and Other Third-Party Costs

Delivery Costs

Accounts Receivable

The following table presents changes in the allowance for doubtful accounts (in thousands):



	Year Ended December 31,
	2017			2018			2019
Beginning balance	$	653		$	105		$	169
Bad debt expense	73			130			1,201
Write-offs, net of recoveries	(621		)	(66		)	(1,115		)
Ending balance	$	105		$	169		$	255

Concentration of Risk

Cash, Cash Equivalents and Restricted Cash

Property and Equipment

Depreciation of property and equipment is determined using the straight-line method over the estimated useful lives of the applicable assets, which are as follows:



Computer equipment:		2–3 years
Furniture and fixtures:		5 years
Leasehold improvements:		Lesser of estimated useful life or life of the lease

Intangible assets

Intangible Assets

Internal Use Software

Internal-Use Software Development Costs

Impairment of long-lived assets

Debt Issuance Costs

Amortization of debt issuance costs included in interest expense, net totaled $0.6 million, $0.3 million and $0.1 million in 2017, 2018 and 2019, respectively.

Deferred Offering Costs

Reduction In Force



	Year Ended December 31,
	2017		2018			2019
Beginning balance	$	—	$	3,144		$	—
Deferred costs	3,144		1,135			196
Recognized against offering proceeds	—		(4,279		)	(196		)
Ending balance	$	3,144	$	—		$	—

Advertising

Research and Development Costs

Stock-Based Compensation

Redeemable Convertible Preferred Stock Warrant Liability

Common Stock Warrant Liability

Fair Value of Financial Instruments


•	Level 1 inputs are quoted prices (unadjusted) in active markets for identical assets or liabilities that the reporting entity has the ability to access at the measurement date.

•


•	Level 3 inputs are unobservable inputs for the asset or liability.

Convertible Promissory Notes

Income Taxes

We have recorded a full valuation allowance related to our net deferred tax assets due to the uncertainty of the ultimate realization of the future benefits of those assets.

SIGNIFICANT ACCOUNTING POLICIES (Tables)

12 Months Ended

Dec. 31, 2019

Accounting Policies [Abstract]

Schedule of allowance for doubtful accounts

The following table presents changes in the allowance for doubtful accounts (in thousands):



	Year Ended December 31,
	2017			2018			2019
Beginning balance	$	653		$	105		$	169
Bad debt expense	73			130			1,201
Write-offs, net of recoveries	(621		)	(66		)	(1,115		)
Ending balance	$	105		$	169		$	255

Schedule of cash and cash equivalents

Schedule of restricted cash

Schedule of property and equipment, useful life

Depreciation of property and equipment is determined using the straight-line method over the estimated useful lives of the applicable assets, which are as follows:



Computer equipment:		2–3 years
Furniture and fixtures:		5 years
Leasehold improvements:		Lesser of estimated useful life or life of the lease

Significant components of property and equipment are as follows (in thousands):



	December 31,
	2018			2019
Computer equipment	$	16,284		$	21,269
Leasehold improvements	5,573			6,960
Furniture and fixtures	913			1,557
Construction in progress	65			1,125
Property and equipment, gross	22,835			30,911
Less accumulated depreciation	(12,605		)	(16,621		)
Property and equipment, net	$	10,230		$	14,290

Schedule of indefinite-lived intangible assets

Capitalized software development costs are as follows (in thousands):



	December 31,
	2018			2019
Capitalized software development costs, gross	$	2,826		$	5,537
Less accumulated amortization	(1,201		)	(1,722		)
Capitalized software development costs, net	$	1,625		$	3,815

Intangible assets are as follows (in thousands):



	December 31,
	2018			2019
Deferred patent costs, gross	$	417		$	448
Less accumulated amortization	(47		)	(59		)
Deferred patent costs, net	$	370		$	389

Schedule of debt issuance costs

Deferred debt issuance costs related to our lines of credit included in other long-term assets are as follows (in thousands):



	December 31,
	2018			2019
Debt issuance costs, gross	$	334		$	388
Less accumulated amortization	(234		)	(271		)
Debt issuance costs, net	$	100		$	117

Deferred debt issuance costs related to our term loans included in debt are as follows (in thousands):



	December 31,
	2018			2019
Debt issuance costs, gross	$	30		$	—
Less accumulated amortization	(10		)	—
Debt issuance costs, net	$	20		$	—

Schedule of future amortization of debt issuance costs

Future amortization of debt issuance costs is as follows (in thousands):



Years Ending December 31,	Amortization
2020	$	87
2021	30
Total	$	117

Schedule of deferred costs



	Year Ended December 31,
	2017		2018			2019
Beginning balance	$	—	$	3,144		$	—
Deferred costs	3,144		1,135			196
Recognized against offering proceeds	—		(4,279		)	(196		)
Ending balance	$	3,144	$	—		$	—

Schedule of restructuring costs



	Year Ended December 31,
	2017		2018			2019
Beginning balance	$	—	$	3,144		$	—
Deferred costs	3,144		1,135			196
Recognized against offering proceeds	—		(4,279		)	(196		)
Ending balance	$	3,144	$	—		$	—

PROPERTY AND EQUIPMENT (Tables)

12 Months Ended

Dec. 31, 2019

Property, Plant and Equipment [Abstract]

Schedule of property and equipment

Depreciation of property and equipment is determined using the straight-line method over the estimated useful lives of the applicable assets, which are as follows:



Computer equipment:		2–3 years
Furniture and fixtures:		5 years
Leasehold improvements:		Lesser of estimated useful life or life of the lease

Significant components of property and equipment are as follows (in thousands):



	December 31,
	2018			2019
Computer equipment	$	16,284		$	21,269
Leasehold improvements	5,573			6,960
Furniture and fixtures	913			1,557
Construction in progress	65			1,125
Property and equipment, gross	22,835			30,911
Less accumulated depreciation	(12,605		)	(16,621		)
Property and equipment, net	$	10,230		$	14,290

Schedule of capital leased assets

Assets acquired under capital leases, included within computer equipment, are as follows (in thousands):



	December 31,
	2018			2019
Capital lease assets, gross	$	1,096		$	1,096
Less accumulated depreciation	(1,047		)	(1,067		)
Capital lease assets, net	$	49		$	29

DEBT (Tables)

12 Months Ended

Dec. 31, 2019

Debt Disclosure [Abstract]

Schedule of long-term debt instruments

Our debt consists of the following (in thousands):



	December 31,
	2018			2019
Lines of credit	$	26,677		$	—
Term loans	19,980			—
Capital leases	57			37
Total debt	46,714			37
Less current portion of long-term debt	(21		)	(24		)
Long-term debt, net of current portion	$	46,693		$	13

Schedule of maturities of debt and capital lease

Aggregate future payments of principal and interest due upon maturity are as follows (in thousands):



Years Ending December 31,	Capital leases
2020	$	24
2021	13
Total debt	$	37

- Definition

Tabular disclosure of long-debt instruments or arrangements, including identification, terms, features, collateral requirements and other information necessary to a fair presentation. These are debt arrangements that originally required repayment more than twelve months after issuance or greater than the normal operating cycle of the entity, if longer.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 1A
-URI http://asc.fasb.org/extlink&oid=114775744&loc=d3e28541-108399

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 6
-URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21506-112644

Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(e),(f))
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

Reference 5: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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Reference 6: http://fasb.org/us-gaap/role/ref/legacyRef
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-URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21521-112644

Reference 7: http://fasb.org/us-gaap/role/ref/legacyRef
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Reference 8: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
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-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=75038535&loc=d3e64711-112823

Reference 9: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
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-URI http://asc.fasb.org/extlink&oid=114775985&loc=d3e28878-108400

Reference 10: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21475-112644

+ Details

STOCK-BASED COMPENSATION (Tables)

12 Months Ended

Dec. 31, 2019

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

Allocation of recognized period costs

The following table summarizes the allocation of stock-based compensation on the consolidated statements of operations (in thousands):



	Year Ended December 31,
	2017		2018		2019
Delivery costs	$	202	$	633	$	711
Sales and marketing expense	1,894		9,358		4,248
Research and development expense	951		4,087		1,619
General and administration expense	2,100		12,712		9,273
Total stock-based compensation expense	$	5,147	$	26,790	$	15,851

Summary of common stock option activity

Common Stock Options

A summary of common stock option activity is as follows (in thousands, except per share amounts):



	Shares		Weighted-Average Exercise Price Per Share		Weighted Average Contractual Life (in years)	Aggregate Intrinsic Value⁽¹⁾(in thousands)
Outstanding - December 31, 2018	1,774		$	20.55
Granted	39		20.64
Exercised	(716	)	16.84			21,399
Forfeited	(31	)	23.95
Cancelled	(66	)	22.37
Outstanding - December 31, 2019	1,000		$	22.99	6.51	$	39,894
Exercisable - December 31, 2019	757		$	22.45	6.29	$	30,586

(1)

The aggregate intrinsic value represents the total pre-tax intrinsic value based on the $62.86 closing price of our common stock as reported on the Nasdaq Global Market on December 31, 2019 that would have been received by option holders had all in-the-money options been exercised on that date.

Summary of RSU activity

A summary of RSU activity, inclusive of performance-based RSUs, is as follows (in thousands, except per share amounts):



	Shares		Weighted-Average Grant Date Fair Value Per Share		Weighted-Average Remaining Contractual Term (in years)	Unamortized Compensation Costs (in thousands)
Unvested - December 31, 2017	—		$	—
Granted	1,309		20.58
Vested	(850	)	21.93
Forfeited/canceled	(78	)	17.97
Unvested - December 31, 2018	381		$	18.11
Granted	1,978		17.78
Vested	(486	)	14.97
Forfeited	(132	)	18.92
Unvested - December 31,2019	1,741		$	18.55
Expected to Vest	1,428		$	19.22	3.09	$	20,389

INCOME TAXES (Tables)

12 Months Ended

Dec. 31, 2019

Income Tax Disclosure [Abstract]

Schedule of domestic and foreign components of income (loss) before income taxes

Domestic and foreign components of loss before income taxes are as follows (in thousands):



	Year Ended December 31,
	2017			2018			2019
Domestic	$	(16,711	)	$	(48,897	)	$	(13,464	)
Foreign	(2,930		)	(4,145		)	(3,680		)
Loss before income taxes	$	(19,641	)	$	(53,042	)	$	(17,144	)

Schedule of components of income tax (expense) benefit

The significant components of income tax (expense) benefit are as follows (in thousands):



	Year Ended December 31,
	2017			2018			2019
Current:
Federal	$	—		$	—		$	—
State	—			—			—
Foreign ⁽¹⁾	—			—			—
Total current	—			—			—
Deferred:
Federal	(28,331		)	6,896			1,326
State	2,345			1,264			622
Foreign	85			916			222
Change in uncertain tax positions	(120		)	(105		)	598
Change in valuation allowance	26,021			(8,971		)	(2,768		)
Total deferred	—			—			—
Income tax benefit	$	—		$	—		$	—

Schedule of effective tax rate

The following table summarizes the significant differences between the U.S. federal statutory tax rate and our effective tax rate:



	Year Ended December 31,
	2017		2018		2019
Tax benefit at federal statutory rate	34.00	%	21.00	%	21.00	%
State income taxes, net of federal benefit	1.82	%	1.91	%	—	%
Change in federal and state statutory rate	(156.32	)%	0.03	%	0.34	%
Foreign rate differential	(1.04	)%	(0.06	)%	(0.20	)%
Other adjustments	(10.93	)%	(5.97	)%	(5.18	)%
Valuation allowance	132.47	%	(16.91	)%	(16.18	)%
Income tax benefit	—	%	—	%	(0.22	)%

Schedule of deferred income taxes

The significant components of deferred income taxes are as follows (in thousands):



	December 31,
	2018			2019
Net operating loss carry-forwards	$	60,718		$	64,348
Allowance for doubtful accounts	26			28
Depreciation and amortization	(856		)	(1,321		)
Stock-based compensation	1,968			2,727
Deferred costs	1,334			2,275
IRC Section 163(j) interest expense limitation	737			436
Other tax credit carry-forward	3,071			1,419
Other temporary differences	465			319
Valuation allowance	(67,463		)	(70,231		)
Net long-term deferred tax liability	$	—		$	—

Summary of changes in valuation allowance

The following table presents changes in our valuation allowance (in thousands):



	Year Ended December 31,
	2017			2018			2019
Beginning balance	$	(84,483	)	$	(58,649	)	$	(67,463	)
Allowance for domestic and foreign net operating loss carry-forwards	(6,509		)	(9,863		)	(3,598		)
Rate change on domestic net operating loss carry-forwards	30,705			(17		)	(32		)
Change in foreign currency	(187		)	157			—
Other changes	1,825			909			862
Ending balance	$	(58,649	)	$	(67,463	)	$	(70,231	)

Schedule of unrecognized tax benefits activity

The following table summarizes the activity related to our gross unrecognized tax benefits that would affect our effective tax rate, if recognized (in thousands):



	Year Ended December 31,
	2017		2018		2019
Beginning balance	$	558	$	678	$	783
Increase related to current year tax position	120		105		(598		)
Ending balance	$	678	$	783	$	185

REDEEMABLE CONVERTIBLE PREFERRED STOCK (Tables)

12 Months Ended

Dec. 31, 2019

Temporary Equity Disclosure [Abstract]

Summary of the change in carrying amount of the outstanding redeemable convertible preferred stock

A summary of the change in carrying amount of the outstanding redeemable convertible preferred stock is as follows (in thousands):



	Series G’ Stock					Series G Stock
	Shares		Amount			Shares		Amount
Balance — December 31, 2017	1,296		$	44,672		346		$	5,110
Conversion of preferred stock to common stock	(1,296	)	(44,672		)	(346	)	(5,218		)
Accretion of redeemable convertible preferred stock	—		—			—		108
Balance — December 31, 2018	—		—			—		—



	Series F/F-R Stock					Series E/E-R Stock					Series D/D-R Stock
	Shares		Amount			Shares		Amount			Shares		Amount
Balance — December 31, 2016	1,199		$	57,958		795		$	29,963		1,396		$	32,642
Accretion of redeemable convertible preferred stock	—		491			—		9			—		86
Balance — December 31, 2017	1,199		$	58,449		795		$	29,972		1,396		$	32,728
Accretion of redeemable convertible preferred stock	—		38			—		1			—		7
Conversion of preferred stock to common stock	(1,199	)	(58,487		)	(795	)	(29,973		)	(1,396	)	(32,735		)
Balance — December 31, 2018	—		$	—		—		$	—		—		$	—



	Series C/C-R Stock					Series B/B-R Stock					Series A/A-R Stock
	Shares		Amount			Shares		Amount			Shares		Amount
Balance — December 31, 2016	1,508		$	18,323		2,247		$	5,286		1,857		$	1,850
Accretion of redeemable convertible preferred stock	—		43			—		2			—		2
Balance — December 31, 2017	1,508		$	18,366		2,247		$	5,288		1,857		$	1,852
Accretion of redeemable convertible preferred stock	—		3			—		—			—		—
Conversion of preferred stock to common stock	(1,508	)	(18,369		)	(2,247	)	(5,288		)	(1,857	)	(1,852		)
Balance — December 31, 2018	—		$	—		—		$	—		—		$	—

COMMON STOCK WARRANTS (Tables)

12 Months Ended

Dec. 31, 2019

Other Liabilities Disclosure [Abstract]

Summary of common stock warrant activity

A summary of common stock warrant activity, exclusive of the common stock warrants issued in connection with our Series G financing is as follows (in thousands, except per share amounts):



	Shares		Weighted-average exercise price per share
Warrants Outstanding - December 31, 2016	583		$	7.52
Granted	17		27.68
Warrants Outstanding - December 31, 2017	600		8.11
Granted⁽¹⁾	644		23.64
Exercised	(349	)	4.69
Redeemable convertible preferred stock warrants converted to common stock warrants	110		12.16
Forfeited/canceled	(138	)	5.85
Warrants Outstanding - December 31, 2018	867		21.89
Exercised	(821	)	21.89
Forfeited/canceled	(34	)	21.29
Warrants Outstanding - December 31, 2019	12		$	23.64

(1)

Performance-based warrants to purchase 644,365 shares of our Series E Stock, which were converted to common stock warrants, vested upon the completion of our IPO in February 2018. These warrants are not included within this table in periods prior to their vesting.

A summary of our preferred stock warrants is as follows (in thousands, except per share amounts):



					December 31,
Preferred Series	Grant date	Expiration date	Exercise price		2017	2018	2019
Series B-R	2/26/2010	2/25/2020	$	2.36	59	—	—
Series D-R	9/21/2012	9/20/2022	$	23.64	38	—	—
Series D-R	9/21/2012	9/20/2022	$	23.64	13	—	—
Total preferred stock warrants					110	—	—

- Definition

Tabular disclosure of warrants or rights issued. Warrants and rights outstanding are derivative securities that give the holder the right to purchase securities (usually equity) from the issuer at a specific price within a certain time frame. Warrants are often included in a new debt issue to entice investors by a higher return potential. The main difference between warrants and call options is that warrants are issued and guaranteed by the company, whereas options are exchange instruments and are not issued by the company. Also, the lifetime of a warrant is often measured in years, while the lifetime of a typical option is measured in months. Disclose the title of issue of securities called for by warrants and rights outstanding, the aggregate amount of securities called for by warrants and rights outstanding, the date from which the warrants or rights are exercisable, and the price at which the warrant or right is exercisable.

+ References + Details

FAIR VALUE MEASUREMENTS (Tables)

12 Months Ended

Dec. 31, 2019

Fair Value Disclosures [Abstract]

Schedule of financial assets and liabilities measured at fair value on a recurring basis



	December 31, 2017
	Level 1		Level 2		Level 3		Total
Liabilities:
Preferred stock warrants⁽¹⁾	$	—	$	—	$	2,285	$	2,285
Common stock warrants⁽¹⁾	—		—		7,945		7,945
Total liabilities	$	—	$	—	$	10,230	$	10,230


(1)	Warrant liabilities were zero as of December 31, 2018 and 2019.

Schedule of reconciliation of the redeemable convertible preferred stock warrant liability



	Preferred Stock Warrants		Common Stock Warrants		Convertible Promissory Notes
Balance at December 31, 2016	$	2,197	$	—	$	72,332
Fair value of convertible promissory notes at issuance	—		—		(44,672		)
Conversion of convertible promissory notes to Series G’ preferred stock	—		—		(24,392		)
Accrued interest on convertible promissory notes	—		—		1,701
Issuance of common stock warrants	—		7,452		—
Changes in fair value	88		493		(4,969		)
Balance at December 31, 2017	$	2,285	$	7,945	$	—



	Preferred Stock Warrants			Common Stock Warrants			Convertible Promissory Notes
Balance at December 31, 2017	$	2,285		$	7,945		$	—
Conversion of convertible promissory notes to common stock	(1,736		)	—			—
Issuance of common stock warrants	(549		)	7,309			—
Changes in fair value	—			(15,254		)	—
Balance at December 31, 2018	$	—		$	—		$	—

Fair value inputs

The following table summarizes key assumptions used in the PWERM for estimating the fair value of our redeemable convertible preferred stock warrant liability:



	Year Ended December 31,
	2017
Cost of debt applicable to convertible promissory notes	—%
Cost of equity applicable to convertible promissory notes	—%
Weighted-average cost of capital applicable to preferred stock warrants	21%
Discount for lack of marketability	7% to 13%
Volatility	55%
Risk-free interest rate	1.2% to 1.4%



	Common stock warrants (issued June 2017)
Weighted-average grant date fair value	$19.04
Significant inputs:
Value of common stock	$30.08
Expected term	10 years
Volatility	50%
Risk-free interest rate	2.2%
Dividend yield	—%

We determined the fair value of these common warrants on the date of IPO using the Black-Scholes option pricing model, which is affected by the fair value of our common stock as well as the following significant inputs:



	February 8, 2018
Weighted-average grant date fair value	$3.91
Significant inputs:
Value of common stock	$13.00
Expected term	5.3 years
Volatility	50%
Risk-free interest rate	2.0%
Dividend yield	—%

Summary of our preferred stock warrants

A summary of common stock warrant activity, exclusive of the common stock warrants issued in connection with our Series G financing is as follows (in thousands, except per share amounts):



	Shares		Weighted-average exercise price per share
Warrants Outstanding - December 31, 2016	583		$	7.52
Granted	17		27.68
Warrants Outstanding - December 31, 2017	600		8.11
Granted⁽¹⁾	644		23.64
Exercised	(349	)	4.69
Redeemable convertible preferred stock warrants converted to common stock warrants	110		12.16
Forfeited/canceled	(138	)	5.85
Warrants Outstanding - December 31, 2018	867		21.89
Exercised	(821	)	21.89
Forfeited/canceled	(34	)	21.29
Warrants Outstanding - December 31, 2019	12		$	23.64

(1)

A summary of our preferred stock warrants is as follows (in thousands, except per share amounts):



					December 31,
Preferred Series	Grant date	Expiration date	Exercise price		2017	2018	2019
Series B-R	2/26/2010	2/25/2020	$	2.36	59	—	—
Series D-R	9/21/2012	9/20/2022	$	23.64	38	—	—
Series D-R	9/21/2012	9/20/2022	$	23.64	13	—	—
Total preferred stock warrants					110	—	—

- Definition

+ References + Details

RELATED PARTIES (Tables)

12 Months Ended

Dec. 31, 2019

Dec. 31, 2018

Schedule of related party transactions

The following table summarizes the participation in the foregoing transactions by our directors, executive officers and holders of more than 5% of any class of our capital stock as of the date of such transactions (in thousands):



Related Party	Shares of Series G Preferred Stock	Shares of Series G’ Preferred Stock	Shares of Common Stock	Warrants to Purchase Common Stock
Entities affiliated with Aimia, Inc.⁽¹⁾	—	382	801	—
Entities affiliated with Polaris Venture Partners⁽²⁾	29	212	—	66
Canaan VIII L.P.⁽³⁾	54	260	—	123
Entities affiliated with Discovery Capital⁽⁴⁾	—	106	—	—
Scott D. Grimes	—	26	—	—
Lynne M. Laube	—	14	—	—
Entities affiliated with Mark A. Johnson⁽⁵⁾	35	15	—	80
John Klinck	6	—	—	13
David Adams	3	—	—	7


(1)	Consists of 159,207 shares of Series G’ redeemable convertible preferred stock issued to Aeroplan Holdings Europe Sàrl, 223,020 shares of Series G’ redeemable convertible preferred stock issued to Aimia EMEA Limited and 801,329 shares of common stock issued to Aimia EMEA Limited.

(2)


(3)	John V. Balen, a member of our board of directors, is a managing member of Canaan Partners VIII LLC, the general partner of Canaan VIII L.P. Mr. Balen does not have voting or investment power over any shares held directly by Canaan VIII L.P.


(4)	Consists of 95,272 shares of Series G’ redeemable convertible preferred stock issued to Discovery Opportunity Master Fund, Ltd. and 11,072 shares of Series G’ redeemable convertible preferred stock issued to Discovery Global Focus Master Fund, Ltd.

(5)

COMMITMENTS AND CONTINGENCIES (Tables)

12 Months Ended

Dec. 31, 2019

Commitments and Contingencies Disclosure [Abstract]

Deferred FI implementation costs

The following table presents changes in deferred FI implementation costs (in thousands):



	December 31,
	2017			2018			2019
Beginning balance	$	8,451		$	13,625		$	15,877
Deferred costs	10,900			9,250			—
Recoveries through FI Share	(4,100		)	(5,380		)	(4,625		)
Amortization	(1,626		)	(1,618		)	(2,869		)
Ending balance	$	13,625		$	15,877		$	8,383

Schedule of Payments to FI Partners



Years Ending December 31,	Amortization
2020	$	3,915
2021	3,509
Total	$	7,424

Future Operating Lease Payments

As of December 31, 2019, future minimum lease payments under non-cancellable operating leases are as follows (in thousands):



Years Ending December 31,	Minimum Lease Payments
2020	$	3,040
2021	2,759
2022	2,808
2023	1,847
2024	1,807
Thereafter	611
Total	$	12,872

EARNINGS PER SHARE (Tables)

12 Months Ended

Dec. 31, 2019

Earnings Per Share [Abstract]

Schedule of antidilutive securities

The following securities have been excluded from the calculation of diluted weighted-average common shares outstanding because the effect is anti-dilutive (in thousands):



	December 31,
	2017	2018	2019
Redeemable convertible preferred stock	10,644	—	—
Common stock options	2,514	1,774	1,000
Common stock warrants	1,245	867	12
Common stock warrants issuable pursuant to Series G Stock financing	547	—	—
Redeemable convertible preferred stock warrants	110	—	—
Restricted stock units	—	381	1,741
Restricted securities units	37	—	—
Common stock issuable pursuant to the ESPP	—	36	7

SEGMENTS (Tables)

12 Months Ended

Dec. 31, 2019

Dec. 31, 2018

Segment Reporting [Abstract]

Schedule of segment reporting information

The following table presents a reconciliation of loss before income taxes presented in accordance with GAAP to adjusted contribution (in thousands):



	Year Ended December 31,
	2017			2018			2019
Adjusted contribution⁽¹⁾⁽²⁾	$	58,744		$	69,450		$	95,219
Minus:
Non-cash equity expense included in FI Share⁽¹⁾	—			2,519			—
Amortization of deferred FI implementation costs⁽¹⁾	1,626			1,618			2,869
Delivery costs	7,012			10,632			12,893
Sales and marketing expense	31,927			41,878			43,828
Research and development expense	12,150			16,210			11,699
General and administration expense	20,100			34,228			36,720
Depreciation and amortization expense	3,028			3,282			4,535
Total non-operating expense (income)	2,542			12,125			(181		)
Loss before income taxes	$	(19,641	)	$	(53,042	)	$	(17,144	)

(1)

Non-cash equity expense included in FI Share and amortization of deferred FI implementation costs are excluded from FI Share and other third-party costs, which is shown above in our reconciliation of GAAP revenue to non-GAAP adjusted contribution.

The following table provides information regarding our reportable segments (in thousands):



	Year Ended December 31,
	2017		2018		2019
Cardlytics Direct:
Adjusted contribution⁽²⁾	$	55,184	$	69,364	$	95,219
Plus: FI Share and other third-party costs ⁽¹⁾⁽²⁾	67,207		79,959		115,211
Revenue	$	122,391	$	149,323	$	210,430
Other Platform Solutions:
Adjusted contribution⁽²⁾	$	3,560	$	86	$	—
Plus: FI Share and other third-party costs ⁽¹⁾⁽²⁾	4,414		1,275		—
Revenue	$	7,974	$	1,361	$	—
Total:
Adjusted contribution⁽²⁾	$	58,744	$	69,450	$	95,219
Plus: FI Share and other third-party costs ⁽¹⁾⁽²⁾	71,621		81,234		115,211
Revenue	$	130,365	$	150,684	$	210,430

(1)

Adjusted FI Share and other third-party costs presented above represents GAAP FI Share and other third-party data costs less a non-cash equity expense included in FI Share and amortization of deferred FI implementation costs, which are detailed below in our reconciliation of GAAP loss before income taxes to adjusted contribution.

Schedule of revenue by geographic areas

The following tables provide geographical information (in thousands):



	Year Ended December 31,
	2017		2018		2019
Revenue:
United States	$	113,509	$	131,563	$	186,864
United Kingdom	16,856		19,121		23,566
Total	$	130,365	$	150,684	$	210,430



	December 31,
	2018		2019
Property and equipment:
United States	$	9,794	$	12,052
United Kingdom	436		2,010
India	—		228
Total	$	10,230	$	14,290

REVENUE (Tables)

12 Months Ended

Dec. 31, 2019

Revenue from Contract with Customer [Abstract]

Disaggregation of Revenue [Table Text Block]

The following table summarizes revenue by pricing model (in thousands):



	Year Ended December 31,
	2017		2018		2019
Cost per Served Sale	$	81,830	$	101,087	$	143,754
Cost per Redemption	33,822		43,389		63,295
Other	14,713		6,208		3,381
Revenue	$	130,365	$	150,684	$	210,430

NATURE OF OPERATIONS (Details) - USD ($)						12 Months Ended
NATURE OF OPERATIONS (Details) - USD ($)	Sep. 11, 2019	Feb. 14, 2018	Feb. 14, 2018	Feb. 13, 2018	Jan. 26, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	May 31, 2017	Feb. 28, 2017	May 04, 2012
Debt Instrument [Line Items]
Proceeds from issuance of common stock, threshold					$ 70,000,000.0
Common stock, shares authorized (in shares)					100,000,000	100,000,000			83,000,000
Par value (in usd per share)					$ 0.0001	$ 0.0001	$ 0.0001
Preferred stock, par or stated value per share (in usd per share)						$ 0.0001
Shares authorized (in shares)					25,000,000				96,131,002	82,683,212
Sale of stock, number of shares issued in transaction (in shares)	1,904,154	421,355	5,821,355
Proceeds from IPO		$ 5,500,000	$ 75,700,000
Proceeds from IPO, net			66,100,000
Sale of stock, discounts and commissions			5,300,000
Issuance costs	$ 200,000		$ 4,300,000			$ 196,000	$ 4,279,000	$ 0
Preferred stock, shares authorized (in shares)							10,000,000
Proceeds from Issuance Seconday Public Offering, Net	$ 61,300,000
IPO
Debt Instrument [Line Items]
Sale of stock, number of shares issued in transaction (in shares)				5,400,000
Sale of stock, price per share (in usd per share)				$ 13.00
Proceeds from IPO				$ 70,200,000
Over-Allotment Option
Debt Instrument [Line Items]
Sale of stock, number of shares issued in transaction (in shares)	404,154	810,000
SPO [Member]
Debt Instrument [Line Items]
Sale of stock, discounts and commissions	$ 3,200,000
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Exercised	1,194,365
Share-based Compensation Arrangement by Share-based Payment Award, Option, Nonvested, Weighted Average Exercise Price	$ 34.00
Cardlytics UK
Debt Instrument [Line Items]
Collaboration Agreement, income (loss), percentage											50.00%

SIGNIFICANT ACCOUNTING POLICIES - Foreign Currency (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Accounting Policies [Abstract]
Foreign Currency Transaction (Gain) Loss	$ (0.8)	$ 1.2	$ (1.3)

SIGNIFICANT ACCOUNTING POLICIES - Revenue (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Concentration Risk [Line Items]
Capitalized software development costs, net	$ 3,815	$ 1,625

SIGNIFICANT ACCOUNTING POLICIES - Consumer Incentives (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Accounting Policies [Abstract]
Consumer incentives, expense	$ 105.6	$ 68.3	$ 61.2

SIGNIFICANT ACCOUNTING POLICIES - Accounts Receivable (Details) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Allowance for Doubtful Accounts Receivable [Roll Forward]
Beginning balance	$ 169	$ 105	$ 653
Bad debt expense	1,201	130	73
Write-offs, net of recoveries	(1,115)	(66)	(621)
Ending balance	255	169	105
Unbilled receivables	$ 600	$ 400	$ 100

SIGNIFICANT ACCOUNTING POLICIES - Cash, Cash Equivalents and Restricted Cash (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Accounting Policies [Abstract]
Cash and cash equivalents	$ 104,458	$ 39,623	$ 21,262
Restricted cash	129	20,247	0
Cash, cash equivalents and restricted cash	$ 104,587	$ 59,870	$ 21,262	$ 22,968

SIGNIFICANT ACCOUNTING POLICIES - Intangible Assets (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2019 USD ($) patent	Dec. 31, 2018 USD ($) patent	Dec. 31, 2013 patent	Dec. 31, 2017 USD ($)
Accounting Policies [Abstract]
Number of patents \| patent	4	1	3
Finite-lived intangible assets, not yet capitalized		$ 300		$ 200
Deferred patent costs, gross	$ 448	417
Less accumulated amortization	(59)	(47)
Deferred patent costs, net	$ 389	$ 370

SIGNIFICANT ACCOUNTING POLICIES - Capitalized Software (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Capitalized Computer Software, Gross	$ 5,537	$ 2,826
Capitalized software development costs, gross	10	0	$ 61
Less accumulated amortization	(1,722)	(1,201)
Capitalized software development costs, net	$ 3,815	$ 1,625

SIGNIFICANT ACCOUNTING POLICIES - Debt Issuance Costs (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	May 21, 2018
Debt Instrument [Line Items]
Loss on extinguishment of debt		$ 900
Amortization of financing costs charged to interest expense	$ 95	282	$ 560
2019	87
2020	30
Total	117
Lines of credit
Debt Instrument [Line Items]
Debt issuance costs, gross	388	334
Less accumulated amortization	(271)	(234)
Debt issuance costs, net	117	100
Term loans
Debt Instrument [Line Items]
Debt issuance costs, gross	0	30
Less accumulated amortization	0	(10)
Debt issuance costs, net	$ 0	$ 20
2016 Line of Credit and 2016 Term Loan
Debt Instrument [Line Items]
Debt issuance costs, net				$ 100

SIGNIFICANT ACCOUNTING POLICIES - Deferred Offering Costs (Details) - USD ($) $ in Thousands			12 Months Ended
	Sep. 11, 2019	Feb. 14, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Deferred Financial Institution Costs [Roll Forward]
Beginning balance			$ 0	$ 3,144	$ 0
Deferred costs			196	1,135	3,144
Recognized against offering proceeds	$ (200)	$ (4,300)	(196)	(4,279)	0
Ending balance			$ 0	$ 0	$ 3,144

SIGNIFICANT ACCOUNTING POLICIES - Reduction in Force (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Restructuring Cost and Reserve [Line Items]
Stock-based compensation expense	$ 15,851	$ 26,790	$ 5,147
Delivery costs
Restructuring Cost and Reserve [Line Items]
Stock-based compensation expense	711	633	202
Sales and marketing expense
Restructuring Cost and Reserve [Line Items]
Stock-based compensation expense	4,248	9,358	1,894
Research and development expense
Restructuring Cost and Reserve [Line Items]
Stock-based compensation expense	1,619	4,087	951
General and administration expense
Restructuring Cost and Reserve [Line Items]
Stock-based compensation expense	$ 9,273	$ 12,712	$ 2,100

SIGNIFICANT ACCOUNTING POLICIES - Advertising costs (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Accounting Policies [Abstract]
Advertising expense	$ 1.4	$ 0.9	$ 0.7

SIGNIFICANT ACCOUNTING POLICIES - Fair Value of Financial Instruments (Details) - USD ($) $ / shares in Units, $ in Millions	1 Months Ended		12 Months Ended
	Aug. 31, 2018	May 31, 2017	Dec. 31, 2019	Dec. 31, 2018	Aug. 08, 2018	May 31, 2013
Class of Stock [Line Items]
Exercise of common stock warrants (in shares)			17,659,000	0
Exercise price of warrants (in usd per share)						$ 23.64
Series G Stock
Class of Stock [Line Items]
Exercise of common stock warrants (in shares)	792,434
Conversion of securities to common stock (in shares)	792,434
Exercise price of warrants (in usd per share)	$ 0.0004				$ 0.0004
Issuance of stock	$ 15.3	$ 11.9

PROPERTY AND EQUIPMENT (Details) - USD ($) $ in Thousands	12 Months Ended
PROPERTY AND EQUIPMENT (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 30,911	$ 22,835
Less accumulated depreciation	(16,621)	(12,605)
Property, Plant and Equipment, Net	14,290	10,230
Capital lease assets, gross	1,096	1,096
Less accumulated depreciation	(1,067)	(1,047)
Capital lease assets, net	29	49
Depreciation expense	4,000	3,000	$ 3,000
Computer equipment
Property, Plant and Equipment [Line Items]
Property and equipment, gross	21,269	16,284
Leasehold improvements
Property, Plant and Equipment [Line Items]
Property and equipment, gross	6,960	5,573
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Property and equipment, gross	1,557	913
Construction in progress
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 1,125	$ 65

DEBT - Schedule of Debt (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018	May 21, 2018
Debt Instrument [Line Items]
Total debt	$ 37	$ 46,714
Less current portion of long-term debt	(24)	(21)
Long-term debt, net of current portion	13	46,693
Lines of credit
Debt Instrument [Line Items]
Total debt	0	26,677	$ 27,400
Debt issuance costs, net	117	100
Term loans
Debt Instrument [Line Items]
Total debt	0	19,980
Debt issuance costs, net	0	20
Capital leases
Debt Instrument [Line Items]
Total debt	$ 37	$ 57

DEBT - Narrative (Details) - USD ($)	12 Months Ended			14 Months Ended
DEBT - Narrative (Details) - USD ($)	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Sep. 30, 2019	May 31, 2019	May 14, 2019	May 21, 2018	Sep. 30, 2016	Jul. 31, 2016
Debt Instrument [Line Items]
Document Period End Date	Dec. 31, 2019
Cash paid for interest	$ 1,266,000	$ 9,733,000	$ 873,000
Maximum borrowing capacity, percentage of accounts receivable	85.00%
Revenue, threshold				$ 240,000,000.0
Repayments of lines of credit	$ 46,698,000	52,581,000	99,000
Loss on extinguishment of debt		900,000
Decrease in fair value of convertible promissory notes	0	0	1,244,000
Lines of credit
Debt Instrument [Line Items]
Line Of Credit Facility, Covenant, Minimum 12 Month Revenue	210,000,000.0
Line of Credit Facility, Maximum Month-end Outstanding Amount	255,000,000.0
2016 Line of Credit and 2016 Term Loan
Debt Instrument [Line Items]
Debt issuance costs, net							$ 100,000
Lines of credit
Debt Instrument [Line Items]
Maximum borrowing capacity	40,000,000.0
Debt issuance costs, gross	388,000	334,000
Debt issuance costs, net	$ 117,000	100,000
Debt instrument, interest rate	4.25%
Commitment fee percentage	0.15%
Debt instrument, interest rate increase event of default	3.00%
Line of credit facility, remaining borrowing capacity	$ 40,000,000.0
Debt Instrument, Annual Principal Payment					$ 10,000,000.0
Lines of credit \| Loan Facility, Threshold Two \| Prime Rate
Debt Instrument [Line Items]
Basis spread on variable rate	0.50%
Lines of credit \| 2016 Line of Credit
Debt Instrument [Line Items]
Maximum borrowing capacity								$ 50,000,000.0
Loss on extinguishment of debt		100,000
Term loans
Debt Instrument [Line Items]
Debt instrument, face amount							20,000,000.0
Debt issuance costs, gross	$ 0	30,000
Debt issuance costs, net	$ 0	20,000
Debt instrument, interest rate	2.00%
Debt Instrument, Unamortized Premium, Current						$ 10,000,000.0
Term loans \| Prime Rate
Debt Instrument [Line Items]
Basis spread on variable rate	2.75%
Term loans \| 2016 Term Loan
Debt Instrument [Line Items]
Debt instrument, face amount									$ 24,000,000.0
Loss on extinguishment of debt		$ 800,000
Revolving Credit Facility \| Lines of credit
Debt Instrument [Line Items]
Maximum borrowing capacity							$ 30,000,000.0
Line of Credit, Current						$ 40,000,000.0
Convertible Promissory Notes
Debt Instrument [Line Items]
Paid-in-king interest			$ 1,700,000

DEBT - Future Payments (Details) $ in Thousands	Dec. 31, 2019 USD ($)
Capital leases
2019	$ 24
2020	13
Total principal payments	$ 37

STOCK-BASED COMPENSATION - Narrative (Details) $ / shares in Units, $ in Thousands				1 Months Ended		2 Months Ended	3 Months Ended		12 Months Ended
	Jan. 01, 2020 shares	Jan. 01, 2019 shares	Feb. 08, 2018 $ / shares shares	Aug. 31, 2018 shares	Feb. 28, 2018 USD ($)	Mar. 02, 2020 shares	Dec. 31, 2018 USD ($) user shares	Mar. 31, 2018 tranche shares	Dec. 31, 2019 USD ($) user shares	Dec. 31, 2018 USD ($) user shares	Dec. 31, 2017 USD ($) $ / shares shares	Dec. 31, 2016 USD ($) $ / shares	Mar. 03, 2020 USD ($)	Jan. 31, 2018 shares	Sep. 30, 2017 $ / shares	May 31, 2017 shares	May 30, 2017 shares	May 15, 2017 $ / shares	Feb. 28, 2017 $ / shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Document Period End Date									Dec. 31, 2019
Number of shares authorized (in shares)			1,875,000
Number of shares remaining available for issuance (in shares)			61,247
Number of shares authorized, annual increase									5.00%
Number of additional shares authorized (in shares)	1,327,352	1,345,631
Amounts accrued for capitalized software development costs \| $									$ 100
Expiration period									10 years
Value of stock (in usd per share) \| $ / shares											$ 26.74	$ 24.48			$ 24.24			$ 30.44	$ 27.68
Weighted-average grant date fair value (in usd per share) \| $ / shares			$ 3.91								$ 12.11
Options vested in period, fair value \| $									$ 4,800	$ 6,000	$ 4,300
Compensation not yet recognized \| $									$ 2,800
Compensation cost not yet recognized									1 year 1 month 6 days
Stock Issued During Period, Shares, Employee Stock Ownership Plan									154,601	177,238
Issuance of ESPP (in shares)	265,470,000								267,823
Restricted stock units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation cost not yet recognized									3 years 1 month 2 days
Granted (in shares)									1,978,000		1,309,000
Unvested PSU (in shares)							381,000		1,741,000	381,000	0
Forfeited, prior to FI MAU (in shares)									132,000		78,000
Vested (in shares)									486,000		850,000
Compensation not yet recognized, awards other than options \| $							$ 4,500		$ 20,389	$ 4,500
Awards granted \| $												$ 1,000
Restricted stock units \| Share-based Compensation Award, Tranche One
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted (in shares)								434,377,000	725,832
Performance-based restricted share unit
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of tranches \| tranche								2
Granted (in shares)								437,500
Unvested PSU (in shares)							875,000		1,252,500	875,000
Vested (in shares)							850,000
Performance-based restricted share unit \| Share-based Compensation Award, Tranche One
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award, performance conditions \| user							70,000,000.0		0.50	70,000,000.0
Forfeited, prior to FI MAU (in shares)										25,000
Performance-based restricted share unit \| Share-based Compensation Award, Tranche Two
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award, performance conditions \| user							85,000,000.0		0.25	85,000,000.0
Stock option expense \| $									$ 18,600
Restricted securities units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
RSU, service condition period										6 years
Award period for sale of company or IPO										5 years
Stock option expense \| $					$ 500
Stock issued during period, RSU (in shares)				37,406
Common stock issuable pursuant to the ESPP
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares authorized, annual increase							1.00%			1.00%
Purchase price of common stock, percent			85.00%
ESPP, number of shares authorized, annual increase (in shares)							500,000			500,000
Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Value of stock (in usd per share) \| $ / shares											$ 24.60
Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Value of stock (in usd per share) \| $ / shares											$ 28.16
2008 Stock Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares authorized (in shares)														4,020,000		3,495,000	3,120,000
Employees and non-employee directors \| Restricted stock units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation cost not yet recognized									3 years 1 month 2 days	2 years 4 months 24 days
Subsequent Event \| Restricted stock units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted (in shares)						188,422
Compensation not yet recognized, awards other than options \| $													$ 15,900

STOCK-BASED COMPENSATION - Allocation of Stock-based Compensation (Details) - USD ($) $ / shares in Units, $ in Thousands		12 Months Ended
	Jun. 28, 2019	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Monthly Average Closing Price, Common Stock, Threshold	$ 62.86
Total stock-based compensation expense		$ 15,851	$ 26,790	$ 5,147
Delivery costs
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation expense		711	633	202
Sales and marketing expense
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation expense		4,248	9,358	1,894
Research and development expense
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation expense		1,619	4,087	951
General and administration expense
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation expense		$ 9,273	$ 12,712	$ 2,100

STOCK-BASED COMPENSATION - Fair Value Assumptions (Details) - $ / shares		12 Months Ended
	Feb. 08, 2018	Dec. 31, 2019	Dec. 31, 2017	Sep. 30, 2017	May 15, 2017	Feb. 28, 2017	Dec. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted-average grant date fair value (in usd per share)	$ 3.91		$ 12.11
Significant inputs:
Value of stock (in usd per share)			$ 26.74	$ 24.24	$ 30.44	$ 27.68	$ 24.48
Expected term			7 years
Volatility, minimum		11.00%	50.00%
Volatility, maximum		47.00%	51.00%
Risk-free interest rate, minimum		0.00%	0.70%
Risk-free interest rate, maximum		2.80%	2.20%
Minimum
Significant inputs:
Value of stock (in usd per share)			$ 24.60
Maximum
Significant inputs:
Value of stock (in usd per share)			$ 28.16

STOCK-BASED COMPENSATION - Summary of Common Stock Option Activity (Details) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2019 USD ($) $ / shares shares
Shares
Beginning balance (in shares) \| shares	1,774
Granted (in shares) \| shares	39
Exercised (in shares) \| shares	(716)
Forfeited (in shares) \| shares	(31)
Canceled (in shares) \| shares	(66)
Ending balance (in shares) \| shares	1,000
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Number of Exercisable Options \| shares	757
Weighted-Average Exercise Price
Beginning balance (in usd per share) \| $ / shares	$ 20.55
Share-based Compensation Arrangements by Share-based Payment Award, Options, Grants in Period, Weighted Average Exercise Price \| $ / shares	20.64
Exercised (in usd per share) \| $ / shares	16.84
Forfeited (in usd per share) \| $ / shares	23.95
Canceled (in usd per share) \| $ / shares	22.37
Ending balance (in usd per share) \| $ / shares	22.99
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Exercise Price \| $ / shares	$ 22.45
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition	1 year 1 month 6 days
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Intrinsic Value \| $	$ 21,399
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Intrinsic Value \| $	39,894
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Exercisable, Aggregate Intrinsic Value \| $	$ 30,586
Employee Stock Option [Member]
Weighted-Average Exercise Price
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition	6 years 6 months 3 days
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Remaining Contractual Term	6 years 3 months 14 days

STOCK-BASED COMPENSATION - Summary of RSU Activity (Details) $ / shares in Units, $ in Thousands	1 Months Ended	2 Months Ended	3 Months Ended		12 Months Ended
	Feb. 28, 2018 USD ($)	Mar. 02, 2020 $ / shares shares	Dec. 31, 2018 USD ($) user $ / shares shares	Mar. 31, 2018 $ / shares shares	Dec. 31, 2019 USD ($) user $ / shares shares	Dec. 31, 2018 USD ($) user $ / shares shares	Dec. 31, 2017 $ / shares shares	Mar. 03, 2020 USD ($)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Exercisable, Aggregate Intrinsic Value \| $					$ 30,586
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition					1 year 1 month 6 days
Document Period End Date					Dec. 31, 2019
Restricted stock units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Exercisable, Aggregate Intrinsic Value \| $					$ 109,500
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Outstanding, Aggregate Intrinsic Value \| $					$ 89,800
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition					3 years 1 month 2 days
Shares
Unvested — Beginning balance (in shares)		1,741,000		0	381,000	0
Granted (in shares)					1,978,000		1,309,000
Vested (in shares)					(486,000)		(850,000)
Forfeited (in shares)					(132,000)		(78,000)
Unvested — Ending balance (in shares)			381,000		1,741,000	381,000	0
Weighted-Average Grant Date Fair Value
Unvested — Beginning balance (in usd per share) \| $ / shares		$ 18.55		$ 0	$ 18.11	$ 0
Granted (in usd per share) \| $ / shares					17.78		$ 20.58
Vested (in usd per share) \| $ / shares					14.97		21.93
Forfeited (in usd per share) \| $ / shares					18.92		17.97
Unvested — Ending balance (in usd per share) \| $ / shares			$ 18.11		$ 18.55	$ 18.11	$ 0
Employee Service Share-based Compensation, Nonvested Awards, Compensation Not yet Recognized, Share-based Awards Other than Options \| $			$ 4,500		$ 20,389	$ 4,500
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Outstanding, Number					1,428,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Exercisable, Weighted Average Exercise Price \| $ / shares					$ 19.22
Performance Shares [Member]
Shares
Unvested — Beginning balance (in shares)		1,252,500			875,000
Granted (in shares)				437,500
Vested (in shares)			(850,000)
Unvested — Ending balance (in shares)			875,000		1,252,500	875,000
Restricted securities units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock or Unit Option Plan Expense \| $	$ 500
Subsequent Event \| Restricted stock units
Shares
Granted (in shares)		188,422
Weighted-Average Grant Date Fair Value
Employee Service Share-based Compensation, Nonvested Awards, Compensation Not yet Recognized, Share-based Awards Other than Options \| $								$ 15,900
Share-based Compensation Award, Tranche Three [Member] \| Performance Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-Based Compensation Arrangement By Share-Based Payment Award, Non-Option Equity Instruments, Performance Conditions \| user					0.25
Share-based Compensation Award, Tranche Two \| Performance Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-Based Compensation Arrangement By Share-Based Payment Award, Non-Option Equity Instruments, Performance Conditions \| user			85,000,000.0		0.25	85,000,000.0
Stock or Unit Option Plan Expense \| $					$ 18,600
Share-based Compensation Award, Tranche One \| Restricted stock units
Shares
Granted (in shares)				434,377,000	725,832
Share-based Compensation Award, Tranche One \| Performance Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-Based Compensation Arrangement By Share-Based Payment Award, Non-Option Equity Instruments, Performance Conditions \| user			70,000,000.0		0.50	70,000,000.0
Shares
Forfeited (in shares)						(25,000)
Employees and non-employee directors \| Restricted stock units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition					3 years 1 month 2 days	2 years 4 months 24 days

INCOME TAXES - Domestic and Foreign Components (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Domestic	$ (13,464)	$ (48,897)	$ (16,711)
Foreign	(3,680)	(4,145)	(2,930)
Loss before income taxes	$ (17,144)	$ (53,042)	$ (19,641)

INCOME TAXES - Components of Income Tax Expense (Benefit) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Current:
Federal	$ 0	$ 0	$ 0
State	0	0	0
Foreign	0	0	0
Total current	0	0	0
Deferred:
Federal	1,326	6,896	(28,331)
State	622	1,264	2,345
Foreign	222	916	85
Change in uncertain tax positions	598	(105)	(120)
Change in valuation allowance	(2,768)	(8,971)	26,021
Total deferred	0	0	0
Income tax benefit	$ 0	$ 0	$ 0

INCOME TAXES - Effective Income Tax Rate (Details)	12 Months Ended
INCOME TAXES - Effective Income Tax Rate (Details)	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Tax benefit at federal statutory rate	21.00%	21.00%	34.00%
State income taxes, net of federal benefit	0.00%	1.91%	1.82%
Change in federal and state statutory rate	0.34%	0.03%	(156.32%)
Foreign rate differential	(0.20%)	(0.06%)	(1.04%)
Other adjustments	(5.18%)	(5.97%)	(10.93%)
Valuation allowance	(16.18%)	(16.91%)	132.47%
Income tax benefit	(0.22%)	0.00%	0.00%

INCOME TAXES - Deferred Tax Assets (Liabilities) (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Net operating loss carry-forwards	$ 64,348	$ 60,718
Allowance for doubtful accounts	28	26
Depreciation and amortization	(1,321)	(856)
Stock-based compensation	2,727	1,968
Change in fair value of convertible promissory notes	2,275	1,334
IRC Section 163(j) interest expense limitation	436	737
Other tax credit carry-forward	1,419	3,071
Other temporary differences	319	465
Valuation allowance	(70,231)	(67,463)	$ (58,649)	$ (84,483)
Net long-term deferred tax liability	$ 0	$ 0

INCOME TAXES - Change in Valuation Allowance (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Valuation Allowance [Roll Forward]
Beginning balance	$ (67,463)	$ (58,649)	$ (84,483)
Allowance for domestic and foreign net operating loss carry-forwards	(3,598)	(9,863)	(6,509)
Rate change on domestic net operating loss carry-forwards	(32)	(17)	30,705
Change in foreign currency	0	157	(187)
Other changes	862	909	1,825
Ending balance	$ (70,231)	$ (67,463)	$ (58,649)

INCOME TAXES - Narrative (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Operating Loss Carryforwards [Line Items]
Tax credits	$ 1,300	$ 700	$ 800
Cash and cash equivalents	104,458	39,623	$ 21,262
Cardlytics UK
Operating Loss Carryforwards [Line Items]
Cash and cash equivalents	4,800
Federal
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards	266,800	249,800
State
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards	98,400	90,500
Foreign
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards	$ 12,100	$ 13,900

INCOME TAXES - Unrecognized Tax Benefits (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Beginning balance	$ 783	$ 678	$ 558
Increase related to current year tax position	(598)	(105)	(120)
Ending balance	$ 185	$ 783	$ 678

REDEEMABLE CONVERTIBLE PREFERRED STOCK - Outstanding Stock (Details) - USD ($) $ in Thousands	1 Months Ended		3 Months Ended	9 Months Ended	12 Months Ended
	Aug. 31, 2018	May 31, 2017	Jun. 30, 2017	Sep. 30, 2017	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Increase (Decrease) in Temporary Equity [Roll Forward]
Issuance of Series G and Series G’ Stock (in shares)					(486,000)	(1,296,000)
Issuance of Series G and Series G’ Stock					$ (61,309)	$ (66,101)
Conversion of preferred stock to common stock				$ (1,735)			$ (24,392)
Document Period End Date					Dec. 31, 2019
Series G’ Stock
Increase (Decrease) in Temporary Equity [Roll Forward]
Beginning balance (in shares)					0	1,296,000
Beginning balance					$ 0	$ 44,672
Issuance of Series G and Series G’ Stock						(44,672)
Accretion of redeemable convertible preferred stock						$ 0
Ending balance (in shares)						0	1,296,000
Ending balance						$ 0	$ 44,672
Series G Stock
Increase (Decrease) in Temporary Equity [Roll Forward]
Beginning balance (in shares)					0	346,000
Beginning balance					$ 0	$ 5,110
Issuance of Series G and Series G’ Stock (in shares)		(346,334)				(346,000)
Issuance of Series G and Series G’ Stock						$ (5,218)
Accretion of redeemable convertible preferred stock						$ 108
Conversion of preferred stock to common stock (in shares)	(792,434)
Deemed dividend related to beneficial conversion feature			$ 4,500
Ending balance (in shares)						0	346,000
Ending balance						$ 0	$ 5,110
Series F/F-R Stock
Increase (Decrease) in Temporary Equity [Roll Forward]
Beginning balance (in shares)				1,199,000	0	1,199,000	1,199,000
Beginning balance				$ 57,958	$ 0	$ 58,449	$ 57,958
Accretion of redeemable convertible preferred stock						$ 38
Conversion of preferred stock to common stock							$ (491)
Ending balance (in shares)						0	1,199,000
Ending balance						$ 0	$ 58,449
Series E/E-R Stock
Increase (Decrease) in Temporary Equity [Roll Forward]
Beginning balance (in shares)				795,000	0	795,000	795,000
Beginning balance				$ 29,963	$ 0	$ 29,972	$ 29,963
Accretion of redeemable convertible preferred stock						$ 1	$ 9
Ending balance (in shares)						0	795,000
Ending balance						$ 0	$ 29,972
Series D/D-R Stock
Increase (Decrease) in Temporary Equity [Roll Forward]
Beginning balance (in shares)				1,396,000	0	1,396,000	1,396,000
Beginning balance				$ 32,642	$ 0	$ 32,728	$ 32,642
Accretion of redeemable convertible preferred stock						$ 7	$ 86
Ending balance (in shares)						0	1,396,000
Ending balance						$ 0	$ 32,728
Series C/C-R Stock
Increase (Decrease) in Temporary Equity [Roll Forward]
Beginning balance (in shares)				1,508,000	0	1,508,000	1,508,000
Beginning balance				$ 18,323	$ 0	$ 18,366	$ 18,323
Accretion of redeemable convertible preferred stock						$ 3	$ 43
Conversion of preferred stock to common stock (in shares)						(1,508,000)
Conversion of preferred stock to common stock						$ (18,369)
Ending balance (in shares)						0	1,508,000
Ending balance						$ 0	$ 18,366
Series B/B-R Stock
Increase (Decrease) in Temporary Equity [Roll Forward]
Beginning balance (in shares)				2,247,000	0	2,247,000	2,247,000
Beginning balance				$ 5,286	$ 0	$ 5,288	$ 5,286
Accretion of redeemable convertible preferred stock						$ 0	$ 2
Conversion of preferred stock to common stock (in shares)						(2,247,000)
Conversion of preferred stock to common stock						$ (5,288)
Ending balance (in shares)						0	2,247,000
Ending balance						$ 0	$ 5,288
Series A/A-R Stock
Increase (Decrease) in Temporary Equity [Roll Forward]
Beginning balance (in shares)				1,857,000	0	1,857,000	1,857,000
Beginning balance				$ 1,850	$ 0	$ 1,852	$ 1,850
Accretion of redeemable convertible preferred stock						$ 0	$ 2
Conversion of preferred stock to common stock (in shares)						(1,857,000)
Conversion of preferred stock to common stock						$ (1,852)
Ending balance (in shares)						0	1,857,000
Ending balance						$ 0	$ 1,852

REDEEMABLE CONVERTIBLE PREFERRED STOCK - Financing and Issuances (Details) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended		3 Months Ended	12 Months Ended
	Aug. 31, 2018	May 31, 2017	Jun. 30, 2017	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Aug. 08, 2018	Jan. 26, 2018	Sep. 30, 2017	May 15, 2017	Feb. 28, 2017	May 31, 2013
Temporary Equity [Line Items]
Shares authorized (in shares)		96,131,002							25,000,000			82,683,212
Shares authorized (in shares)		83,000,000		100,000,000					100,000,000
Issuance costs				$ 196	$ 1,949	$ 2,668
Conversion of stock, shares converted (in shares)		801,329
Exercise price of warrants (in usd per share)													$ 23.64
Exercise of common stock warrants (in shares)				17,659,000	0
Proceeds from issuance of preferred stock				$ 0	$ 0	11,940
Deemed dividend related to beneficial conversion feature						$ 4,488
Issuance of Series G and Series G’ Stock (in shares)				486,000	1,296,000
Value of stock (in usd per share)						$ 26.74	$ 24.48			$ 24.24	$ 30.44	$ 27.68
Series G’ Stock
Temporary Equity [Line Items]
Redeemable convertible preferred stock, par value (in usd per share)		$ 0.0001
Conversion of stock, shares converted (in shares)		1,295,746
Conversion Price (in usd per share)		$ 27.58
Preferred stock, dividend rate (in usd per share)		2.758
Series G Stock
Temporary Equity [Line Items]
Redeemable convertible preferred stock, par value (in usd per share)		$ 0.0001
Issuance costs		$ 100
Shares issued (in shares)		346,334
Class of warrant, numerator input value (in usd per share)		$ 68.9516
Exercise price of warrants (in usd per share)	$ 0.0004							$ 0.0004
Exercise of common stock warrants (in shares)	792,434
Issuance of stock	$ 15,300	$ 11,900
Proceeds from issuance of preferred stock		11,900
Redeemable convertible preferred stock, residual value		4,500
Deemed dividend related to beneficial conversion feature		$ 6,100
Deemed dividend related to beneficial conversion feature			$ 4,500
Issuance of Series G and Series G’ Stock (in shares)		346,334			346,000
Series F/F-R Stock
Temporary Equity [Line Items]
Conversion of stock, shares issued (in shares)							1,198,637
Series E/E-R Stock
Temporary Equity [Line Items]
Conversion of stock, shares issued (in shares)							795,027
Series D/D-R Stock
Temporary Equity [Line Items]
Conversion of stock, shares issued (in shares)							1,395,936
Series C/C-R Stock
Temporary Equity [Line Items]
Conversion of stock, shares issued (in shares)							1,507,906
Series B/B-R Stock
Temporary Equity [Line Items]
Conversion of stock, shares issued (in shares)							2,246,744
Series A/A-R Stock
Temporary Equity [Line Items]
Conversion of stock, shares issued (in shares)							1,856,998
Additional Paid-In Capital
Temporary Equity [Line Items]
Exercise of common stock warrants (in shares)				17,659,000	0
Deemed dividend related to beneficial conversion feature						$ 4,488
Additional Paid-In Capital \| Series G Stock
Temporary Equity [Line Items]
Beneficial conversion feature of stock		$ 4,500
Common stock
Temporary Equity [Line Items]
Exercise of common stock warrants (in shares)				821,000	1,142,000
Issuance of Series G and Series G’ Stock (in shares)				1,904,000	5,821,000
Common stock \| Series E/E-R Stock
Temporary Equity [Line Items]
Conversion of stock, shares issued (in shares)							397,515
Common stock \| Series B/B-R Stock
Temporary Equity [Line Items]
Conversion of stock, shares issued (in shares)							2,121
Common stock \| Series A/A-R Stock
Temporary Equity [Line Items]
Conversion of stock, shares issued (in shares)							12,375

REDEEMABLE CONVERTIBLE PREFERRED STOCK - Protective Provisions, Redemptions, Liquidation and Conversion (Details) - $ / shares	Dec. 31, 2019	May 31, 2017
Series G’ Stock
Temporary Equity [Line Items]
Redemption price per share (in usd per share)	$ 34.4758
Liquidation of business payment per share (in usd per share)	34.4758
Liquidation preference (in usd per share)	103.4274
Series G Stock
Temporary Equity [Line Items]
Shares Issued, Price Per Share		$ 34.4758
Redemption price per share (in usd per share)	34.4758
Liquidation of business payment per share (in usd per share)	68.9516
Liquidation preference (in usd per share)	103.4274
Series F/F-R Stock
Temporary Equity [Line Items]
Redemption price per share (in usd per share)	58.40
Liquidation of business payment per share (in usd per share)	58.40
Liquidation preference (in usd per share)	175.20
Conversion price (in usd per share)	50.0568
Series E/E-R Stock
Temporary Equity [Line Items]
Redemption price per share (in usd per share)	37.7344
Liquidation of business payment per share (in usd per share)	37.7344
Liquidation preference (in usd per share)	113.2032
Conversion price (in usd per share)	37.7344
Series D/D-R Stock
Temporary Equity [Line Items]
Redemption price per share (in usd per share)	23.64
Liquidation of business payment per share (in usd per share)	23.64
Liquidation preference (in usd per share)	70.92
Conversion price (in usd per share)	23.64
Series C/C-R Stock
Temporary Equity [Line Items]
Redemption price per share (in usd per share)	12.2686
Liquidation of business payment per share (in usd per share)	21.4701
Liquidation preference (in usd per share)	36.8058
Conversion price (in usd per share)	12.2686
Series B/B-R Stock
Temporary Equity [Line Items]
Redemption price per share (in usd per share)	2.3567
Liquidation of business payment per share (in usd per share)	2.3567
Liquidation preference (in usd per share)	4.7134
Conversion price (in usd per share)	2.3567
Series A/A-R Stock
Temporary Equity [Line Items]
Liquidation of business payment per share (in usd per share)	1.00
Liquidation preference (in usd per share)	2.00
Conversion price (in usd per share)	1.00
Series G Stock and G’ Stock
Temporary Equity [Line Items]
Conversion price (in usd per share)	$ 34.4758

COMMON STOCK WARRANTS - Warrant Activity (Details) - $ / shares	1 Months Ended	12 Months Ended
	Jun. 30, 2017	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Shares
Warrants outstanding, beginning balance (in shares)		0	110,000
Exercised (in shares)		(644,365)
Warrants outstanding, ending balance (in shares)		0	0	110,000
Common Stock Warrants
Shares
Warrants outstanding, beginning balance (in shares)		867,000	600,000	583,000
Granted (in shares)	17,500		644,000	17,000
Exercised (in shares)		(821,000)		(349,000)
Redeemable convertible preferred stock warrants converted to common stock warrants (in shares)				110,000
Forfeited/cancelled (in shares)		(34,000)		(138,000)
Warrants outstanding, ending balance (in shares)		12,000	867,000	600,000	583,000
Weighted-average exercise price per share
Warrants outstanding, beginning balance (in dollars per share)		$ 21.89	$ 8.11	$ 7.52
Granted (in dollars per share)	$ 27.68		23.64	27.68
Exercised (in dollars per share)		21.89		4.69
Redeemable convertible preferred stock warrants converted to common stock warrants (in dollars per share)				12.16
Forfeited/cancelled (in dollars per share)		21.29		5.85
Warrants outstanding, ending balance (in dollars per share)		$ 23.64	$ 21.89	$ 8.11	$ 7.52
Performance-based Warrants
Shares
Redeemable convertible preferred stock warrants converted to common stock warrants (in shares)					644,365

COMMON STOCK WARRANTS - Narrative (Details) - $ / shares	1 Months Ended	12 Months Ended
	Jun. 30, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2019	May 31, 2013
Class of Warrant or Right [Line Items]
Class of warrant (in shares)		0	110,000		0	644,365
Common Stock Warrants
Class of Warrant or Right [Line Items]
Class of warrant (in shares)		867,000	600,000	583,000	12,000
Warrants issued/granted (in shares)	17,500	644,000	17,000
Exercise price of warrants issued/granted (in dollars per share)	$ 27.68	$ 23.64	$ 27.68
Warrants converted (in shares)			110,000
Exercise price of warrants converted (in dollars per share)			$ 12.16
Series A Common Stock Warrants
Class of Warrant or Right [Line Items]
Warrants converted (in shares)				12,500
Exercise price of warrants converted (in dollars per share)				$ 1.00
Series B Common Stock Warrants
Class of Warrant or Right [Line Items]
Warrants converted (in shares)				25,000
Exercise price of warrants converted (in dollars per share)				$ 2.36
Performance-based Warrants
Class of Warrant or Right [Line Items]
Warrants converted (in shares)				644,365
Class of warrant , unvested (in shares)				644,365
Series E Common Stock Warrants
Class of Warrant or Right [Line Items]
Exercise price of warrants converted (in dollars per share)				$ 23.64

FAIR VALUE MEASUREMENTS - Financial Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2017	Jun. 30, 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term warrant liability	$ 0
Convertible Debt, Fair Value Disclosures		$ 10,230
Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Convertible Debt, Fair Value Disclosures		0
Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Convertible Debt, Fair Value Disclosures		0
Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Convertible Debt, Fair Value Disclosures		10,230
Preferred Stock Warrants
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term warrant liability		2,285
Preferred Stock Warrants \| Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term warrant liability		0
Preferred Stock Warrants \| Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term warrant liability		0
Preferred Stock Warrants \| Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term warrant liability		2,285
Common Stock Warrants
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term warrant liability		7,945	$ 300
Common Stock Warrants \| Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term warrant liability		0
Common Stock Warrants \| Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term warrant liability		0
Common Stock Warrants \| Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term warrant liability		$ 7,945

FAIR VALUE MEASUREMENTS - Instruments Recorded at Fair Value Using Level 3 Inputs (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Preferred Stock Warrants
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value, beginning balance	$ 2,285	$ 2,197
Exercise/Conversion to common stock	(1,736)
Changes in fair value	(549)	88
Fair value, ending balance	0	2,285
Common Stock Warrants
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value, beginning balance	7,945
Issuance of stock	7,309	7,452
Changes in fair value	(15,254)	493
Fair value, ending balance	0	7,945
Convertible Promissory Notes
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value, beginning balance	0	72,332
Exercise/Conversion to common stock		(44,672)
Accrued interest on convertible promissory notes		1,701
Changes in fair value	0	(4,969)
Fair value, ending balance	0	0
Convertible Promissory Notes \| Common Stock
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Exercise/Conversion to common stock	$ 0	$ (24,392)

FAIR VALUE MEASUREMENTS - Fair Value Assumptions (Details)	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Cost of Debt
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Measurement input		0
Cost of Debt \| Minimum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Measurement input			0.12
Cost of Debt \| Maximum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Measurement input			0.17
Cost of Equity
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Measurement input		0
Cost of Equity \| Minimum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Measurement input			0.24
Cost of Equity \| Maximum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Measurement input			0.26
Weighted-average cost of capital applicable to preferred stock warrants
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Measurement input		0.21
Discount for lack of marketability \| Minimum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Measurement input	0.07	0.07	0.08
Discount for lack of marketability \| Maximum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Measurement input	0.13	0.13	0.12
Volatility
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Measurement input		0.55
Risk-free interest rate \| Minimum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Measurement input	0.012	0.012	0.007
Risk-free interest rate \| Maximum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Measurement input	0.014	0.014	0.012

FAIR VALUE MEASUREMENTS - Preferred Stock Warrants (Details) - $ / shares	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	May 31, 2013
Class of Stock [Line Items]
Exercise price of warrants (in usd per share)				$ 23.64
Class of warrant (in shares)	0	0	110,000	644,365
Series B/B-R Stock \| Grant One
Class of Stock [Line Items]
Exercise price of warrants (in usd per share)	$ 2.36
Class of warrant (in shares)	0	0	59,000
Series D/D-R Stock \| Grant One
Class of Stock [Line Items]
Exercise price of warrants (in usd per share)	$ 23.64
Class of warrant (in shares)	0	0	38,000
Series D/D-R Stock \| Grant Two
Class of Stock [Line Items]
Exercise price of warrants (in usd per share)	$ 23.64
Class of warrant (in shares)	0	0	13,000

FAIR VALUE MEASUREMENTS - Narrative (Details) $ / shares in Units, $ in Thousands	1 Months Ended				12 Months Ended
	Aug. 31, 2018 USD ($) $ / shares shares	Feb. 28, 2018 USD ($)	May 31, 2017 USD ($) shares	May 31, 2013 $ / shares shares	Dec. 31, 2019 USD ($) shares	Dec. 31, 2018 USD ($) shares	Dec. 31, 2017 USD ($) $ / shares shares	Aug. 08, 2018 $ / shares	Feb. 08, 2018 $ / shares	Jun. 30, 2017 USD ($) $ / shares shares	Dec. 31, 2016 USD ($)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value per share (in usd per share) \| $ / shares									$ 13.00
Fair value of warrants issued					$ 0
Exercise price of warrants (in usd per share) \| $ / shares				$ 23.64
Exercise of common stock warrants (in shares) \| shares					17,659,000	0
Change in fair value of warrant liabilities, net					$ 0	$ (6,760)	$ (581)
Class of warrant (in shares) \| shares				644,365	0	0	110,000
Warrant, term				10 years
Common Stock Warrants
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value per share (in usd per share) \| $ / shares										$ 30.08
Fair value of warrants issued							$ 7,945			$ 300
Exercise price of warrants (in usd per share) \| $ / shares										$ 27.68
Liability value						$ 0	7,945
Class of warrant (in shares) \| shares										17,500
Stock option expense		$ 2,500
Preferred Stock Warrants
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of warrants issued							2,285
Liability value						0	2,285				$ 2,197
Convertible Promissory Notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liability value						$ 0	$ 0				$ 72,332
Series B/B-R Stock
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value per share (in usd per share) \| $ / shares							$ 26.80		20.18
Conversion of securities to common stock (in shares) \| shares						2,247,000
Series D/D-R Stock
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value per share (in usd per share) \| $ / shares							$ 13.63		$ 10.57
Series G Stock
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Shares issued (in shares) \| shares			346,334
Exercise price of warrants (in usd per share) \| $ / shares	$ 0.0004							$ 0.0004
Liability value			$ 7,500
Exercise of common stock warrants (in shares) \| shares	792,434
Conversion of securities to common stock (in shares) \| shares	792,434
Issuance of stock	$ 15,300		$ 11,900
Change in fair value of warrant liabilities, net					$ 7,300	$ 500
Volatility
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Significant inputs									0.50
Volatility \| Common Stock Warrants
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Significant inputs										0.50
Volatility \| Series G Stock
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Significant inputs			0.59
Discount for lack of marketability \| Series G Stock
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Significant inputs				0.11

FAIR VALUE MEASUREMENTS - Warrants Pricing Model (Details)		1 Months Ended	12 Months Ended
	Feb. 08, 2018 $ / shares	Jun. 30, 2017 $ / shares	Dec. 31, 2017 $ / shares
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Weighted-average grant date fair value (in usd per share)	$ 3.91		$ 12.11
Value of common stock (in usd per share)	$ 13.00
Expected term	5 years 3 months 18 days
Volatility
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Significant inputs	0.50
Risk-free interest rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Significant inputs	0.020
Dividend yield
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Significant inputs	0
Common Stock Warrants
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Weighted-average grant date fair value (in usd per share)		$ 19.04
Value of common stock (in usd per share)		$ 30.08
Expected term		10 years
Common Stock Warrants \| Volatility
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Significant inputs		0.50
Common Stock Warrants \| Risk-free interest rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Significant inputs		0.022
Common Stock Warrants \| Dividend yield
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Significant inputs		0

RELATED PARTIES - Narrative (Details) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended			12 Months Ended
	Feb. 28, 2018	May 31, 2017	May 31, 2013	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Aug. 31, 2018	Aug. 08, 2018
Related Party Transaction [Line Items]
Proceeds from issuance of preferred stock				$ 0	$ 0	$ 11,940
Issuance of Series G and Series G’ Stock (in shares)				486,000	1,296,000
Conversion of stock, shares converted (in shares)		801,329
Warrant, term			10 years
Class of warrant (in shares)			644,365	0	0	110,000
Exercise price of warrants (in usd per share)			$ 23.64
Series G Stock
Related Party Transaction [Line Items]
Proceeds from issuance of preferred stock		$ 11,900
Issuance of Series G and Series G’ Stock (in shares)		346,334			346,000
Exercise price of warrants (in usd per share)							$ 0.0004	$ 0.0004
Series G’ Stock
Related Party Transaction [Line Items]
Conversion of stock, shares converted (in shares)		1,295,746
Series E
Related Party Transaction [Line Items]
Issuance of Series G and Series G’ Stock (in shares)			397,515
Common Stock Warrants
Related Party Transaction [Line Items]
Stock option expense	$ 2,500
Stockholders' Equity \| Shareholder Concentration Risk
Related Party Transaction [Line Items]
Concentration risk					5.00%

RELATED PARTIES - Series G / Series G’ (Details) - shares	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	May 31, 2013
Related Party Transaction [Line Items]
Class of warrant (in shares)	0	0	110,000	644,365
Series G Stock
Related Party Transaction [Line Items]
Shares outstanding (in shares)		0	346,000
Series G’ Stock
Related Party Transaction [Line Items]
Shares outstanding (in shares)		0	1,296,000
Aimia Inc. \| Affiliated Entity
Related Party Transaction [Line Items]
Shares outstanding (in shares)	801,000
Class of warrant (in shares)	0
Aimia Inc. \| Series G Stock \| Affiliated Entity
Related Party Transaction [Line Items]
Shares outstanding (in shares)	0
Aimia Inc. \| Series G’ Stock \| Affiliated Entity
Related Party Transaction [Line Items]
Shares outstanding (in shares)	382,000
Polaris Venture Partners \| Affiliated Entity
Related Party Transaction [Line Items]
Shares outstanding (in shares)	0
Class of warrant (in shares)	66,000
Polaris Venture Partners \| Series G Stock \| Affiliated Entity
Related Party Transaction [Line Items]
Shares outstanding (in shares)	29,000
Polaris Venture Partners \| Series G’ Stock \| Affiliated Entity
Related Party Transaction [Line Items]
Shares outstanding (in shares)	212,000
Canaan VIII L.P. \| Affiliated Entity
Related Party Transaction [Line Items]
Shares outstanding (in shares)	0
Class of warrant (in shares)	123,000
Canaan VIII L.P. \| Series G Stock \| Affiliated Entity
Related Party Transaction [Line Items]
Shares outstanding (in shares)	54,000
Canaan VIII L.P. \| Series G’ Stock \| Affiliated Entity
Related Party Transaction [Line Items]
Shares outstanding (in shares)	260,000
Discovery Capital \| Affiliated Entity
Related Party Transaction [Line Items]
Shares outstanding (in shares)	0
Class of warrant (in shares)	0
Discovery Capital \| Series G Stock \| Affiliated Entity
Related Party Transaction [Line Items]
Shares outstanding (in shares)	0
Discovery Capital \| Series G’ Stock \| Affiliated Entity
Related Party Transaction [Line Items]
Shares outstanding (in shares)	106,000
Scott D. Grimes \| Scott D. Grimes
Related Party Transaction [Line Items]
Shares outstanding (in shares)	0
Class of warrant (in shares)	0
Scott D. Grimes \| Series G Stock \| Scott D. Grimes
Related Party Transaction [Line Items]
Shares outstanding (in shares)	0
Scott D. Grimes \| Series G’ Stock \| Scott D. Grimes
Related Party Transaction [Line Items]
Shares outstanding (in shares)	26,000
Lynne M. Laube \| Lynne M. Laube
Related Party Transaction [Line Items]
Shares outstanding (in shares)	0
Class of warrant (in shares)	0
Lynne M. Laube \| Series G Stock \| Lynne M. Laube
Related Party Transaction [Line Items]
Shares outstanding (in shares)	0
Lynne M. Laube \| Series G’ Stock \| Lynne M. Laube
Related Party Transaction [Line Items]
Shares outstanding (in shares)	14,000
Entities affiliated with Mark A. Johnson \| Affiliated Entity
Related Party Transaction [Line Items]
Shares outstanding (in shares)	0
Class of warrant (in shares)	80,000
Entities affiliated with Mark A. Johnson \| Series G Stock \| Affiliated Entity
Related Party Transaction [Line Items]
Shares outstanding (in shares)	35,000
Entities affiliated with Mark A. Johnson \| Series G’ Stock \| Affiliated Entity
Related Party Transaction [Line Items]
Shares outstanding (in shares)	15,000
Mark A. Johnson \| Affiliated Entity
Related Party Transaction [Line Items]
Class of warrant (in shares)	13,273
Mark A. Johnson \| Series G Stock \| Affiliated Entity
Related Party Transaction [Line Items]
Shares outstanding (in shares)	5,801
John Klinck \| Director
Related Party Transaction [Line Items]
Shares outstanding (in shares)	0
Class of warrant (in shares)	13,000
John Klinck \| Series G Stock \| Director
Related Party Transaction [Line Items]
Shares outstanding (in shares)	6,000
John Klinck \| Series G’ Stock \| Director
Related Party Transaction [Line Items]
Shares outstanding (in shares)	0
David Adams \| Director
Related Party Transaction [Line Items]
Shares outstanding (in shares)	0
Class of warrant (in shares)	7,000
David Adams \| Series G Stock \| Director
Related Party Transaction [Line Items]
Shares outstanding (in shares)	3,000
David Adams \| Series G’ Stock \| Director
Related Party Transaction [Line Items]
Shares outstanding (in shares)	0
Aeroplan Holdings Europe Sàrl \| Series G’ Stock \| Affiliated Entity
Related Party Transaction [Line Items]
Shares outstanding (in shares)	159,207
Aimia EMEA Limited \| Affiliated Entity
Related Party Transaction [Line Items]
Shares outstanding (in shares)	801,329
Aimia EMEA Limited \| Series G’ Stock \| Affiliated Entity
Related Party Transaction [Line Items]
Shares outstanding (in shares)	223,020
Polaris Venture Partners V, L.P. \| Affiliated Entity
Related Party Transaction [Line Items]
Class of warrant (in shares)	64,038
Polaris Venture Partners V, L.P. \| Series G Stock \| Affiliated Entity
Related Party Transaction [Line Items]
Shares outstanding (in shares)	27,988
Polaris Venture Partners V, L.P. \| Series G’ Stock \| Affiliated Entity
Related Party Transaction [Line Items]
Shares outstanding (in shares)	205,020
Polaris Venture Partners Entrepreneurs’ Fund V, L.L. \| Affiliated Entity
Related Party Transaction [Line Items]
Class of warrant (in shares)	1,247
Polaris Venture Partners Entrepreneurs’ Fund V, L.L. \| Series G Stock \| Affiliated Entity
Related Party Transaction [Line Items]
Shares outstanding (in shares)	545
Polaris Venture Partners Entrepreneurs’ Fund V, L.L. \| Series G’ Stock \| Affiliated Entity
Related Party Transaction [Line Items]
Shares outstanding (in shares)	3,995
Polaris Venture Partners Founders’ Fund V, L.P. \| Affiliated Entity
Related Party Transaction [Line Items]
Class of warrant (in shares)	438
Polaris Venture Partners Founders’ Fund V, L.P. \| Series G Stock \| Affiliated Entity
Related Party Transaction [Line Items]
Shares outstanding (in shares)	191
Polaris Venture Partners Founders’ Fund V, L.P. \| Series G’ Stock \| Affiliated Entity
Related Party Transaction [Line Items]
Shares outstanding (in shares)	1,404
Polaris Venture Partners Special Founders’ Fund V, L.P. \| Affiliated Entity
Related Party Transaction [Line Items]
Class of warrant (in shares)	641
Polaris Venture Partners Special Founders’ Fund V, L.P. \| Series G Stock \| Affiliated Entity
Related Party Transaction [Line Items]
Shares outstanding (in shares)	280
Polaris Venture Partners Special Founders’ Fund V, L.P. \| Series G’ Stock \| Affiliated Entity
Related Party Transaction [Line Items]
Shares outstanding (in shares)	2,050
Discovery Opportunity Master Fund, Ltd. \| Series G’ Stock \| Affiliated Entity
Related Party Transaction [Line Items]
Shares outstanding (in shares)	95,272
Discovery Global Opportunity Master Fund, Ltd. \| Series G’ Stock \| Affiliated Entity
Related Party Transaction [Line Items]
Shares outstanding (in shares)	11,072
TTP Fund II, L.P. \| Series G’ Stock \| Affiliated Entity
Related Party Transaction [Line Items]
Shares outstanding (in shares)	15,045
TTV Ivy Holdings, LLC \| Affiliated Entity
Related Party Transaction [Line Items]
Class of warrant (in shares)	66,365
TTV Ivy Holdings, LLC \| Series G Stock \| Affiliated Entity
Related Party Transaction [Line Items]
Shares outstanding (in shares)	29,005

RELATED PARTIES - Agreements with Aimia Inc. and Affiliated Entities (Details) $ in Millions	12 Months Ended
	Dec. 31, 2019 USD ($) shares
Related Party Transaction [Line Items]
Proceeds from Warrant Exercises \| $	$ 15.2
Class of Warrant or Right, Exercised \| shares	644,365

VARIABLE INTEREST ENTITY (Details) - USD ($) $ in Thousands	12 Months Ended
VARIABLE INTEREST ENTITY (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Variable Interest Entity [Line Items]
Delivery costs	$ 12,893	$ 10,632	$ 7,012
Sales and marketing expense	43,828	41,878	31,927
General and administration expense	36,720	34,228	20,100
Allocation of revenue less FI Share and other third-party costs	210,430	150,684	130,365
Net cash used in operating activities	11,457	(18,995)	(22,102)
Net cash used in investing activities	$ (11,020)	$ (7,342)	$ (1,647)

COMMITMENTS AND CONTINGENCIES - Narrative (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Loss Contingencies [Line Items]
Financial institution partners, payments to partners, not yet earned	$ 1,000
Decrease to FI share liability	(14,301)	$ (3,742)	$ (804)
Financial Institution Share Commitment
Loss Contingencies [Line Items]
FI share commitment	$ 10,000

COMMITMENTS AND CONTINGENCIES - Deferred FI Implementation Costs (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Deferred Financial Institution Costs [Roll Forward]
Beginning balance	$ 15,877	$ 13,625	$ 8,451
Deferred costs	0	9,250	10,900
Recoveries through FI Share	(4,625)	(5,380)	(4,100)
Amortization	(2,869)	(1,618)	(1,626)
Ending balance	$ 8,383	$ 15,877	$ 13,625

COMMITMENTS AND CONTINGENCIES - Payments to FI Partners (Details) $ in Thousands	Dec. 31, 2019 USD ($)
Commitments and Contingencies Disclosure [Abstract]
2020	$ 3,915
2021	3,509
Total	$ 7,424

COMMITMENTS AND CONTINGENCIES - Operating Leases (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Aug. 31, 2013 USD ($) ft²
Property Subject to or Available for Operating Lease [Line Items]
Operating leases, rent expense	$ 3,000	$ 3,000	$ 3,000
2019	3,040
2020	2,759
2021	2,808
2022	1,847
2023	1,807
Thereafter	611
Total	$ 12,872
Corporate Headquarters, Atlanta, GA
Property Subject to or Available for Operating Lease [Line Items]
Lease, term of contract				130 years
Area of real estate property (sq ft) \| ft²				76,880
Tenant improvement allowance				$ 3,800
Total				$ 16,000

EARNINGS PER SHARE (Details) - shares shares in Thousands	12 Months Ended
EARNINGS PER SHARE (Details) - shares shares in Thousands	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Redeemable convertible preferred stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities (in shares)	0	0	10,644
Common stock options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities (in shares)	1,000	1,774	2,514
Common stock warrants
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities (in shares)	12	867	1,245
Common stock warrants \| Series G’ Stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities (in shares)	0	0	547
Redeemable convertible preferred stock warrants
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities (in shares)	0	0	110
Restricted stock units
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities (in shares)	1,741	381	0
Restricted securities units
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities (in shares)	0	0	37
Common stock issuable pursuant to the ESPP
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities (in shares)	7	36	0

SEGMENTS - Narrative (Details) $ in Thousands	12 Months Ended
SEGMENTS - Narrative (Details) $ in Thousands	Dec. 31, 2019 USD ($) segment	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)
Segment Reporting Information [Line Items]
Number of operating segments \| segment	3
Capital expenditures	$ 8,277	$ 5,920	$ 1,215
United Kingdom
Segment Reporting Information [Line Items]
Capital expenditures	$ 2,000	$ 100

SEGMENTS - Revenue by Segment (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Segment Reporting Information [Line Items]
Document Period End Date	Dec. 31, 2019
Adjusted contribution	$ 95,219	$ 69,450	$ 58,744
Plus: FI Share and other third-party costs	115,211	81,234	71,621
Revenues	210,430	150,684	130,365
Cardlytics Direct
Segment Reporting Information [Line Items]
Adjusted contribution	95,219	69,364	55,184
Plus: FI Share and other third-party costs	115,211	79,959	67,207
Revenues	210,430	149,323	122,391
Other Platform Solutions
Segment Reporting Information [Line Items]
Adjusted contribution	0	86	3,560
Plus: FI Share and other third-party costs	0	1,275	4,414
Revenues	$ 0	$ 1,361	$ 7,974
Accounts Receivable [Member] \| Two Customer [Member] [Member] \| Customer Concentration Risk [Member]
Segment Reporting Information [Line Items]
Concentration Risk, Percentage	11.00%

SEGMENTS - Adjusted Contribution Reconciliation (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Segment Reporting [Abstract]
Document Period End Date	Dec. 31, 2019
Adjusted contribution	$ 95,219	$ 69,450	$ 58,744
Non-cash equity expense included in FI Share	0	2,519	0
Amortization of deferred FI implementation costs	2,869	1,618	1,626
Delivery costs	12,893	10,632	7,012
Sales and marketing expense	43,828	41,878	31,927
Research and development expense	11,699	16,210	12,150
General and administration expense	36,720	34,228	20,100
Depreciation and amortization expense	4,535	3,282	3,028
Total other expense	(181)	12,125	2,542
Loss before income taxes	$ (17,144)	$ (53,042)	$ (19,641)

SEGMENTS - Geographical Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Segment Reporting Information [Line Items]
Document Period End Date	Dec. 31, 2019
Revenues	$ 210,430	$ 150,684	$ 130,365
Property and equipment	14,290	10,230
United States
Segment Reporting Information [Line Items]
Revenues	186,864	131,563	113,509
Property and equipment	12,052	9,794
United Kingdom
Segment Reporting Information [Line Items]
Revenues	23,566	19,121	$ 16,856
Property and equipment	2,010	436
INDIA
Segment Reporting Information [Line Items]
Property and equipment	$ 228	$ 0
Largest FI Partner Three [Member] [Member] \| Supplier Concentration Risk [Member] \| Financial Institution Partner [Member]
Segment Reporting Information [Line Items]
Concentration Risk, Percentage	10.00%		12.00%

REVENUE (Details) - USD ($) $ in Thousands	12 Months Ended
REVENUE (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Consumer incentives, expense	$ 105,600	$ 68,300	$ 61,200
Revenue from Contract with Customer, Excluding Assessed Tax	210,430	150,684	130,365
Cost per Served Sales [Member]
Revenue from Contract with Customer, Excluding Assessed Tax	143,754	101,087	81,830
Cost per Redemption [Member]
Revenue from Contract with Customer, Excluding Assessed Tax	63,295	43,389	33,822
Cost Other [Member]
Revenue from Contract with Customer, Excluding Assessed Tax	$ 3,381	$ 6,208	$ 14,713

Concentration of Risk (Details) - Financial Institution Partner [Member] - Supplier Concentration Risk [Member]	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Largest FI Partner One [Member]
Concentration Risk [Line Items]
Concentration risk	36.00%	64.00%	63.00%
Largest FI Partner Two [Member]
Concentration Risk [Line Items]
Concentration risk	42.00%	6.00%
Largest FI Partner Three [Member] [Member]
Concentration Risk [Line Items]
Concentration risk	10.00%		12.00%

Label	Element	Value
Adjustments to Additional Paid in Capital, Preferred Stock Warrant Conversion, Common Stock Warrant	cdlx_AdjustmentstoAdditionalPaidinCapitalPreferredStockWarrantConversionCommonStockWarrant	$ 196,594,000
Additional Paid-in Capital [Member]
Stock Issued During Period, Value, Conversion of Convertible Securities	us-gaap_StockIssuedDuringPeriodValueConversionOfConvertibleSecurities	1,735,000
Adjustments to Additional Paid in Capital, Preferred Stock Warrant Conversion, Common Stock Warrant	cdlx_AdjustmentstoAdditionalPaidinCapitalPreferredStockWarrantConversionCommonStockWarrant	196,588,000
Common Stock [Member]
Stock and Warrants Issued During Period, Value, Preferred Stock and Warrants	us-gaap_StockAndWarrantsIssuedDuringPeriodValuePreferredStockAndWarrants	$ 0
Stock Issued During Period, Shares, Conversion of Convertible Securities	us-gaap_StockIssuedDuringPeriodSharesConversionOfConvertibleSecurities	10,643,000
Stock Issued During Period, Value, Conversion of Convertible Securities	us-gaap_StockIssuedDuringPeriodValueConversionOfConvertibleSecurities	$ 6,000