DEBT (Subordinate Debt) (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2019	Dec. 31, 2018
Debt Instrument [Line Items]
Net premium and debt issue costs	$ (7,558)
Carrying Value	140,239	$ 149,187
Subordinated Loan \| MMA Financial Holdings, Inc. Debt [Member]
Debt Instrument [Line Items]
Principal amount of debt	89,379
Net premium and debt issue costs	7,784
Carrying Value	97,163
Subordinated Loan \| Mfh Issue 1 [Member]
Debt Instrument [Line Items]
Principal amount of debt	26,393
Net premium and debt issue costs	2,369
Carrying Value	$ 28,762
Maturity Date	March 30, 2035
Coupon Interest Rate	3-month LIBOR plus 2.0%
Subordinated Loan \| Mfh Issue 2 [Member]
Debt Instrument [Line Items]
Principal amount of debt	$ 23,999
Net premium and debt issue costs	2,165
Carrying Value	$ 26,164
Maturity Date	April 30, 2035
Coupon Interest Rate	3-month LIBOR plus 2.0%
Subordinated Loan \| Mfh Issue 3 [Member]
Debt Instrument [Line Items]
Principal amount of debt	$ 13,834
Net premium and debt issue costs	1,153
Carrying Value	$ 14,987
Maturity Date	July 30, 2035
Coupon Interest Rate	3-month LIBOR plus 2.0%
Subordinated Loan \| Mfh Issue 4 [Member]
Debt Instrument [Line Items]
Principal amount of debt	$ 25,153
Net premium and debt issue costs	2,097
Carrying Value	$ 27,250
Maturity Date	July 30, 2035
Coupon Interest Rate	3-month LIBOR plus 2.0%

Debt Instrument, Principal Amount

No definition available.

Name:	mmac_DebtInstrumentPrincipalAmount
Namespace Prefix:	mmac_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The amount of debt discount (net of debt premium) and debt issuance cost that was originally recognized at the issuance of the instrument that has yet to be amortized.

+ References

No definition available.

+ Details

Name:	mmac_DebtInstrumentUnamortizedDiscountPremiumAndDebtIssuanceCostNet
Namespace Prefix:	mmac_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Description of the interest rate as being fixed or variable, and, if variable, identification of the index or rate on which the interest rate is based and the number of points or percentage added to that index or rate to set the rate, and other pertinent information, such as frequency of rate resets.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22(a)(1))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

Name:	us-gaap_DebtInstrumentInterestRateTerms
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

Name:	us-gaap_DebtInstrumentLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Description of the maturity date of the debt instrument including whether the debt matures serially and, if so, a brief description of the serial maturities.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22(a)(2))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

Name:	us-gaap_DebtInstrumentMaturityDateDescription
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(a)(16))
-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(16))
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(22))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

Name:	us-gaap_LongTermDebt
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Details

Name:	us-gaap_LongtermDebtTypeAxis=us-gaap_SubordinatedDebtMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=mmac_MmaFinancialHoldingsInc.DebtMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=mmac_MfhIssue1Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=mmac_MfhIssue2Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=mmac_MfhIssue3Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=mmac_MfhIssue4Member
Namespace Prefix:
Data Type:	na
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Period Type: