Loans Receivable - Loan Receivables Acquired By Geographics (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Net book value	$ 239,207	$ 49,929
Percentage	100.00%	100.00%
Northeast [Member]
Net book value	$ 92,550	$ 11,092
Percentage	39.00%	22.00%
Southeast [Member]
Net book value	$ 80,960	$ 38,837
Percentage	34.00%	78.00%
West [Member]
Net book value	$ 29,453
Percentage	12.00%
Southwest [Member]
Net book value	$ 23,849
Percentage	10.00%
Northwest [Member]
Net book value	$ 12,395
Percentage	5.00%