| Cover | Feb. 24, 2021 |
| Cover [Abstract] | |
| Document Type | 8-K |
| Document Period End Date | Feb. 24, 2021 |
| Entity Registrant Name | TrueCar, Inc. |
| Entity Incorporation, State or Country Code | DE |
| Entity File Number | 001-36449 |
| Entity Tax Identification Number | 04-3807511 |
| Entity Address, Address Line One | 120 Broadway |
| Entity Address, Address Line Two | Suite 200 |
| Entity Address, City or Town | Santa Monica |
| Entity Address, State or Province | CA |
| Entity Address, Postal Zip Code | 90401 |
| City Area Code | 800 |
| Local Phone Number | 200-2000 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Title of 12(b) Security | Common Stock, par value $0.0001 per share |
| Trading Symbol | TRUE |
| Security Exchange Name | NASDAQ |
| Entity Emerging Growth Company | false |
| Entity Central Index Key | 0001327318 |
| Amendment Flag | false |
