| Document And Entity Information | Mar. 23, 2022 |
| Cover [Abstract] | |
| Document Type | 8-K |
| Amendment Flag | false |
| Document Period End Date | Mar. 23, 2022 |
| Entity Registrant Name | First Advantage Corporation |
| Entity Central Index Key | 0001210677 |
| Entity Emerging Growth Company | true |
| Entity File Number | 001-31666 |
| Entity Incorporation, State or Country Code | DE |
| Entity Tax Identification Number | 84-3884690 |
| Entity Address, Address Line One | 1 Concourse Parkway NE |
| Entity Address, Address Line Two | Suite 200 |
| Entity Address, City or Town | Atlanta |
| Entity Address, State or Province | GA |
| Entity Address, Postal Zip Code | 30328 |
| City Area Code | 888 |
| Local Phone Number | 314-9761 |
| Entity Information, Former Legal or Registered Name | Not applicable |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Entity Ex Transition Period | false |
| Title of 12(b) Security | Common Stock, $0.001 par value per share |
| Trading Symbol | FA |
| Security Exchange Name | NASDAQ |
