Servicing of Residential Loans - Schedule of Servicing Rights Carried at Amortized Cost (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Servicing Asset at Amortized Cost, Balance [Roll Forward]
Amortization of servicing rights (1)	$ (21,801)	$ (26,827)	$ (43,101)
Mortgage Loan Class [Member]
Servicing Asset at Amortized Cost, Balance [Roll Forward]
Balance at beginning of the year	99,302	121,364	161,782
Servicing rights capitalized upon deconsolidation of Residual Trusts		3,133
Sales	(318)
Amortization of servicing rights (1)	(24,363)	(25,195)	(40,418)
Balance at end of the year	74,621	99,302	121,364
Impairment of servicing rights	4,000
Reverse Loan Class [Member]
Servicing Asset at Amortized Cost, Balance [Roll Forward]
Balance at beginning of the year	7,258	9,311	11,994
Servicing rights capitalized upon deconsolidation of Residual Trusts		0
Sales	0
Amortization of servicing rights (1)	(1,753)	(2,053)	(2,683)
Balance at end of the year	$ 5,505	$ 7,258	$ 9,311