| Document and Entity Information | Feb. 26, 2021 | Sep. 30, 2020 |
| Entity Information [Line Items] | ||
| Document Type | 8-K | |
| Amendment Flag | false | |
| Document Period End Date | Feb. 26, 2021 | |
| Entity Registrant Name | CARDLYTICS, INC. | |
| Entity Registrant Name | CDLX | |
| Entity Central Index Key | 0001666071 | |
| Entity Emerging Growth Company | false | |
| Entity Incorporation, State or Country Code | DE | |
| Entity File Number | 001-38386 | |
| Entity Tax Identification Number | 26-3039436 | |
| Entity Address, Address Line One | 675 Ponce de Leon Avenue NE, Suite 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 | 798-5802 | |
| Written Communications | false | |
| Soliciting Material | false | |
| Pre-commencement Tender Offer | false | |
| Title of 12(b) Security | Common Stock | |
| Security Exchange Name | NASDAQ | |
| Pre-commencement Issuer Tender Offer | false |
