| Document And Entity Information - USD ($) | 12 Months Ended | ||
| Dec. 31, 2020 | Apr. 21, 2021 | Jun. 30, 2020 | |
| Document Type | 10-K/A | ||
| Document Annual Report | true | ||
| Document Transition Report | false | ||
| Document Period End Date | Dec. 31, 2020 | ||
| Entity Registrant Name | MMA CAPITAL HOLDINGS, INC. | ||
| Entity Incorporation, State or Country Code | DE | ||
| Entity File Number | 001-11981 | ||
| Entity Tax Identification Number | 52-1449733 | ||
| Entity Address, Address Line One | 3600 O’Donnell Street, Suite 600 | ||
| Entity Address, City or Town | Baltimore | ||
| Entity Address, State or Province | MD | ||
| Entity Address, Postal Zip Code | 21224 | ||
| City Area Code | 443 | ||
| Local Phone Number | 263-2900 | ||
| Entity Current Reporting Status | Yes | ||
| Entity Interactive Data Current | Yes | ||
| Entity Filer Category | Non-accelerated Filer | ||
| Entity Small Business | true | ||
| Entity Emerging Growth Company | false | ||
| Entity Central Index Key | 0001003201 | ||
| Current Fiscal Year End Date | --12-31 | ||
| Document Fiscal Period Focus | FY | ||
| Document Fiscal Year Focus | 2020 | ||
| Amendment Flag | false | ||
| Entity Common Stock, Shares Outstanding | 5,742,286 | ||
| Entity Shell Company | false | ||
| Entity Well-known Seasoned Issuer | No | ||
| Entity Voluntary Filers | No | ||
| Entity Public Float | $ 111,130,141 | ||
| ICFR Auditor Attestation Flag | false | ||
| Common Stock [Member] | |||
| Title of 12(b) Security | Common Shares, no par value | ||
| Trading Symbol | MMAC | ||
| Security Exchange Name | NASDAQ | ||
| Common Stock Purchase Rights [Member] | |||
| Title of 12(b) Security | Common Stock Purchase Rights | ||
| Trading Symbol | MMAC | ||
| Security Exchange Name | NASDAQ |
