Cover Page - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2020	Feb. 28, 2021	Dec. 31, 2019	Jun. 28, 2019	Jan. 26, 2018
Cover [Abstract]
Document Type	10-K
Document Annual Report	true
Document Period End Date	Dec. 31, 2020
Current Fiscal Year End Date	--12-31
Document Transition Report	false
Entity File Number	001-38386
Entity Registrant Name	CARDLYTICS, INC.
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
Title of 12(b) Security	Common Stock
Trading Symbol	CDLX
Security Exchange Name	NASDAQ
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Public Float				$ 1,800.0
Entity Common Stock, Shares Outstanding (in shares)		27,903,828
Common stock, par or stated value per share (in usd per share)	$ 0.0001		$ 0.0001		$ 0.0001
Entity Central Index Key	0001666071
Amendment Flag	false
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	FY