| Document and Entity Information | Mar. 04, 2022 |
| Document And Entity Information [Line Items] | |
| Amendment Flag | false |
| Entity Central Index Key | 0001805833 |
| Document Type | 8-K |
| Document Period End Date | Mar. 4, 2022 |
| Entity Registrant Name | System1, Inc. |
| Entity Incorporation State Country Code | DE |
| Entity File Number | 001-39331 |
| Entity Tax Identification Number | 98-1531250 |
| Entity Address, Address Line One | 4235 Redwood Avenue |
| Entity Address, City or Town | Marina Del Rey |
| Entity Address, State or Province | CA |
| Entity Address, Postal Zip Code | 90066 |
| City Area Code | (310) |
| Local Phone Number | 924-6037 |
| Written Communications | false |
| Soliciting Material | false |
| Pre Commencement Tender Offer | false |
| Pre Commencement Issuer Tender Offer | false |
| Entity Emerging Growth Company | true |
| Entity Ex Transition Period | false |
| Common Stock [Member] | |
| Document And Entity Information [Line Items] | |
| Security 12b Title | Class A Common Stock, $0.0001 par value per share |
| Trading Symbol | SST |
| Security Exchange Name | NYSE |
| Warrant [Member] | |
| Document And Entity Information [Line Items] | |
| Security 12b Title | Redeemable warrants, each whole warrant exercisable for one Class A Common Stock share at an exercise price of $11.50 per share |
| Trading Symbol | SST.WS |
| Security Exchange Name | NYSE |
