Name:	mmab_DisposalGroupIncludingDiscontinuedOperationIncomeFromReoOperations
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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

Amount of income (loss) from a disposal group, consolidated fund venture.

No definition available.

Name:	mmab_DisposalGroupIncludingDiscontinuedOperationNetGainsRelatedToConsolidatedFundVenture
Namespace Prefix:	mmab_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

Amount of other gain attributable to disposal group.

No definition available.

Name:	mmab_DisposalGroupIncludingDiscontinuedOperationOtherGain
Namespace Prefix:	mmab_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

Amount of sublease income attributable to the disposal group, including a component of the entity (discontinued operation).

No definition available.

Name:	mmab_DisposalGroupIncludingDiscontinuedOperationSubleaseIncome
Namespace Prefix:	mmab_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

Amount of other expenses attributable to the disposal group, including a component of the entity (discontinued operation), during the reporting period.

No definition available.

Name:	mmab_OtherDiscontinuedExpenses
Namespace Prefix:	mmab_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Amount of rental expenses attributable to the disposal group, including a component of the entity (discontinued operation), during the reporting period.

No definition available.

Name:	mmab_RentExpense
Namespace Prefix:	mmab_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Details

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

Tax effect of adjustment to an amount previously reported in discontinued operations that is directly related to the disposal of the component in a prior period. Examples of circumstances leading to such adjustments include the resolution of contingencies relating to the terms of the disposal transaction or relating to the operations of the component prior to its disposal, and the settlement of certain employee benefit plan obligations.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 740

-SubTopic 10

-Section 50

-Paragraph 10

-URI http://asc.fasb.org/extlink&oid=6907707&loc=d3e32672-109319

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 205

-SubTopic 20

-Section 45

-Paragraph 4

-URI http://asc.fasb.org/extlink&oid=6892542&loc=d3e1012-107759

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-Publisher FASB

-Name Accounting Standards Codification

-Topic 205

-SubTopic 20

-Section 50

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-URI http://asc.fasb.org/extlink&oid=6360339&loc=d3e1510-107760

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-Publisher FASB

-Name Accounting Standards Codification

-Topic 205

-SubTopic 20

-Section 45

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-Name Accounting Standards Codification

-Topic 740

-SubTopic 20

-Section 45

-Paragraph 2

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=18498875&loc=d3e38679-109324

Name:	us-gaap_DiscontinuedOperationTaxEffectOfAdjustmentToPriorPeriodGainLossOnDisposal
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Amount of operating expenses attributable to the disposal group, including a component of the entity (discontinued operation), during the reporting period.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 205

-SubTopic 20

-Section 50

-Paragraph 1

-Subparagraph (c)

-URI http://asc.fasb.org/extlink&oid=6360339&loc=d3e1361-107760

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Period Type:	duration

Amount of operating income or loss attributable to the disposal group, including a component of the entity (discontinued operation), during the reporting period.

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Period Type:	duration

Amount of rental income attributable to the disposal group, including a component of the entity (discontinued operation).

No definition available.

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Data Type:	xbrli:monetaryItemType
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Period Type:	duration

Amount of sales or other form of revenues attributable to the disposal group, including a component of the entity (discontinued operation), during the reporting period.

Name:	us-gaap_DisposalGroupIncludingDiscontinuedOperationRevenue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

Amount of income (loss) from a disposal group, net of income tax before extraordinary items allocable to noncontrolling interests. Includes, net of tax, income (loss) from operations during the phase-out period, gain (loss) on disposal, provision (or any reversals of earlier provisions) for loss on disposal, and adjustments of a prior period gain (loss) on disposal.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 205

-SubTopic 20

-Section 45

-Paragraph 3

-URI http://asc.fasb.org/extlink&oid=6892542&loc=d3e957-107759

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-Publisher FASB

-Name Accounting Standards Codification

-Topic 944

-SubTopic 225

-Section S99

-Paragraph 1

-Subparagraph (SX 210.7-04.12)

-URI http://asc.fasb.org/extlink&oid=6879464&loc=d3e573970-122913

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-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 04

-Paragraph 13

-Article 7

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 205

-SubTopic 20

-Section 50

-Paragraph 1

-Subparagraph (c)

-URI http://asc.fasb.org/extlink&oid=6360339&loc=d3e1361-107760

Reference 5: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 225

-SubTopic 10

-Section S99

-Paragraph 2

-Subparagraph (SX 210.5-03.14)

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-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 15

-Article 5

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This element represents the overall income (loss) from a disposal group that is classified as a component of the entity, net of income tax, reported as a separate component of income before extraordinary items, which is apportioned to that ownership interest in subsidiary equity which is not attributable to the parent (noncontrolling interest, minority interest). This item includes the following (net of tax): income (loss) from operations during the phase-out period, gain (loss) on disposal, provision (or any reversals of earlier provisions) for loss on disposal, and adjustments of a prior period gain (loss) on disposal.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 810

-SubTopic 10

-Section 45

-Paragraph 19

-URI http://asc.fasb.org/extlink&oid=7656940&loc=SL4569616-111683

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-Publisher FASB

-Name Accounting Standards Codification

-Topic 810

-SubTopic 10

-Section 45

-Paragraph 15

-URI http://asc.fasb.org/extlink&oid=7656940&loc=SL4568447-111683

Name:	us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTaxAttributableToNoncontrollingInterest
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Amount of income (loss) from a disposal group, net of income tax, reported as a separate component of income before extraordinary items after deduction or consideration of the amount allocable to noncontrolling interests. Includes, net of tax, income (loss) from operations during the phase-out period, gain (loss) on disposal, provision (or any reversals of earlier provisions) for loss on disposal, and adjustments of a prior period gain (loss) on disposal.