DEBT (Subordinate Debt) (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2020	Dec. 31, 2019
Debt Instrument [Line Items]
Net premium and debt issue costs	$ 7,272
Carrying Value	$ 223,653	$ 201,816
Subordinated principal (as percent)	2.00%
Subordinated Loan [Member] \| MMA Financial Holdings Inc. Debt [Member]
Debt Instrument [Line Items]
Principal amount of debt	$ 87,605
Net premium and debt issue costs	7,318
Carrying Value	94,923
Subordinated Loan [Member] \| MFH Issue 1 [Member]
Debt Instrument [Line Items]
Principal amount of debt	25,869
Net premium and debt issue costs	2,229
Carrying Value	$ 28,098
Maturity Date	March 30, 2035
Coupon Interest Rate	three-month LIBOR plus 2.0%
Subordinated Loan [Member] \| MFH Issue 2 [Member]
Debt Instrument [Line Items]
Principal amount of debt	$ 23,523
Net premium and debt issue costs	2,034
Carrying Value	$ 25,557
Maturity Date	April 30, 2035
Coupon Interest Rate	three-month LIBOR plus 2.0%
Subordinated Loan [Member] \| MFH Issue 3 [Member]
Debt Instrument [Line Items]
Principal amount of debt	$ 13,559
Net premium and debt issue costs	1,084
Carrying Value	$ 14,643
Maturity Date	July 30, 2035
Coupon Interest Rate	three-month LIBOR plus 2.0%
Subordinated Loan [Member] \| MFH Issue 4 [Member]
Debt Instrument [Line Items]
Principal amount of debt	$ 24,654
Net premium and debt issue costs	1,971
Carrying Value	$ 26,625
Maturity Date	July 30, 2035
Coupon Interest Rate	three-month LIBOR plus 2.0%

Represents the principal amortization percent of debt instrument.

No definition available.

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Namespace Prefix:	mmac_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Debt Instrument, Principal Amount

+ References

No definition available.

+ Details

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://fasb.org/us-gaap/role/ref/legacyRef
-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

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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://fasb.org/us-gaap/role/ref/legacyRef
-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

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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/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
-Paragraph 4
-Subparagraph (b)(3)
-URI http://asc.fasb.org/extlink&oid=109500613&loc=SL6031897-161870

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-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=119400593&loc=d3e572229-122910

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-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 4: http://fasb.org/us-gaap/role/ref/legacyRef
-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

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

- Details

Name:	us-gaap_LongtermDebtTypeAxis=us-gaap_SubordinatedDebtMember
Namespace Prefix:
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- Details

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Namespace Prefix:
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- Details

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Namespace Prefix:
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- Details

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- Details

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- Details

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