Residential Loans - Summary of Activity in Allowance for Losses on Residential Loans (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Allowance for Loan and Lease Losses [Roll Forward]
Provision for loan losses	$ 355	$ (961)	$ (4,737)
Residential Loans
Allowance for Loan and Lease Losses [Roll Forward]
Balance at beginning of period	21,338	25,427	28,504
Charge-offs, net	0	(4,966)	(4,525)
Provision for loan losses	0	877	1,448
Deconsolidation adjustment	(21,338)	0	0
Balance at End of Period	$ 0	$ 21,338	$ 25,427