| Cover | Dec. 10, 2021 | Dec. 09, 2021 |
| Document Type | 8-K | |
| Amendment Flag | false | |
| Document Period End Date | Dec. 9, 2021 | |
| Entity File Number | 001-39462 | |
| Entity Registrant Name | FAST ACQUISITION CORP. | |
| Entity Central Index Key | 0001815737 | |
| Entity Tax Identification Number | 85-1338207 | |
| Entity Incorporation, State or Country Code | DE | |
| Entity Address, Address Line One | 109 Old Branchville Rd. | |
| Entity Address, City or Town | Ridgefield | |
| Entity Address, State or Province | CT | |
| Entity Address, Postal Zip Code | 06877 | |
| City Area Code | 201 | |
| Local Phone Number | 956-1969 | |
| Written Communications | false | |
| Soliciting Material | false | |
| Pre-commencement Tender Offer | false | |
| Pre-commencement Issuer Tender Offer | false | |
| Entity Emerging Growth Company | true | |
| Elected Not To Use the Extended Transition Period | false | |
| Units, each consisting of one share of Class A common stock and one-half of one redeemable warrant | ||
| Title of 12(b) Security | Units, each consisting of one share of Class A common stock and one-half of one redeemable warrant | |
| Trading Symbol | FST.U | |
| Security Exchange Name | NYSE | |
| Class A common stock, par value $0.0001 per share | ||
| Title of 12(b) Security | Class A common stock, par value $0.0001 per share | |
| Trading Symbol | FST | |
| Security Exchange Name | NYSE | |
| Redeemable warrants, each whole warrant exercisable for one share of Class A common stock, each at an exercise price of $11.50 per share | ||
| Title of 12(b) Security | Redeemable warrants, each whole warrant exercisable for one share of Class A common stock, each at an exercise price of $11.50 per share | |
| Trading Symbol | FST WS | |
| Security Exchange Name | NYSE |
