LOANS HFI AND LOANS HFS (Composition of Loans) (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Loans HFI and Loans HFS
UPB	$ 68,050	$ 1,487
Cost basis adjustments, net	(751)	(751)
Loans HFI, net	$ 67,299	$ 736

Cost basis adjustments to loans receivable, including deferred interest and fees, undisbursed portion of loan balance, unamortized costs and premiums and any other cost basis adjustments.

No definition available.

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