Real Estate Owned (REO) and Mortgages Payable - Summary of REO, Net (Detail) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019
Real Estate [Abstract]
Holding costs, net of other income	$ 164	$ 53
(Gains)/losses on sales	(133)	(14)
Valuation adjustments		631
REO, net	$ 31	$ 670

Amount of realized gain (loss) on investment.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 220
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-04.3(a))
-URI http://asc.fasb.org/extlink&oid=120400993&loc=SL114874131-224263

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Balance Type:	credit
Period Type:	duration