LOANS HFI AND LOANS HFS (Carrying Value of Loans) (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
LOANS HFI AND LOANS HFS [Abstract]
Loans held for investment	$ 54,100	$ 67,299
Total loans	$ 54,100	$ 67,299

Loans Receivable Held-for-investment and Held-for-sale, Amount

No definition available.

Name:	mmac_LoansReceivableHeldForInvestmentAndHeldForSaleAmount
Namespace Prefix:	mmac_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant