| Cover | Dec. 06, 2021 |
| Document Type | 8-K |
| Amendment Flag | false |
| Document Period End Date | Dec. 6, 2021 |
| Entity File Number | 001-40116 |
| Entity Registrant Name | MCAP Acquisition Corporation |
| Entity Central Index Key | 0001838672 |
| Entity Tax Identification Number | 85-3978415 |
| Entity Incorporation, State or Country Code | DE |
| Entity Address, Address Line One | 311 South Wacker Drive |
| Entity Address, Address Line Two | Suite 6400 |
| Entity Address, City or Town | Chicago |
| Entity Address, State or Province | IL |
| Entity Address, Postal Zip Code | 60606 |
| City Area Code | 312 |
| Local Phone Number | 258-8300 |
| Written Communications | true |
| 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-third of one Warrant [Member] | |
| Title of 12(b) Security | Units, each consisting of one share of Class A Common Stock and one-third of one Warrant |
| Trading Symbol | MACQU |
| Security Exchange Name | NASDAQ |
| Common Stock [Member] | |
| Title of 12(b) Security | Class A Common Stock, par value $0.0001 per share |
| Trading Symbol | MACQ |
| Security Exchange Name | NASDAQ |
| Warrants, each whole warrant exercisable for one share of Class A Common Stock at an exercise price of $11.50 [Member] | |
| Title of 12(b) Security | Warrants, each whole warrant exercisable for one share of Class A Common Stock at an exercise price of $11.50 |
| Trading Symbol | MACQW |
| Security Exchange Name | NASDAQ |
