| Cover | Dec. 23, 2021 |
| Document Information [Line Items] | |
| Document Type | 8-K |
| Amendment Flag | false |
| Document Period End Date | Dec. 23, 2021 |
| Entity File Number | 001-40116 |
| Entity Registrant Name | AdTheorent Holding Company, Inc. |
| Entity Central Index Key | 0001838672 |
| Entity Tax Identification Number | 85-3978415 |
| Entity Incorporation, State or Country Code | DE |
| Entity Address, Address Line One | 330 Hudson Street |
| Entity Address, Address Line Two | 13th Floor |
| Entity Address, City or Town | New York |
| Entity Address, State or Province | NY |
| Entity Address, Postal Zip Code | 10013 |
| City Area Code | 800 |
| Local Phone Number | 804-1359 |
| 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 | true |
| Entity Information, Former Legal or Registered Name | MCAP Acquisition Corporation |
| Common Class A [Member] | |
| Document Information [Line Items] | |
| Title of 12(b) Security | Class A common stock, par value $0.0001 per share |
| Trading Symbol | ADTH |
| Security Exchange Name | NASDAQ |
| Warrant [Member] | |
| Document Information [Line Items] | |
| Title of 12(b) Security | Warrants to purchase Class A common stock |
| Trading Symbol | ADTHW |
| Security Exchange Name | NASDAQ |
| Former Address [Member] | |
| Document Information [Line Items] | |
| 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 |
