Servicing of Residential Loans - Schedule of Servicing Rights Carried at Amortized Cost (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Servicing Asset at Amortized Cost, Balance [Roll Forward]
Amortization of servicing rights	$ (9,926)	$ (2,625)	$ (14,951)	$ (7,236)
Mortgage Loan
Servicing Asset at Amortized Cost, Balance [Roll Forward]
Balance at beginning of the period			74,621	99,302
Sales			0	(103)
Amortization of servicing rights	(2,900)	(5,200)	(5,162)	(10,626)
Impairment of servicing rights	(7,700)
Balance at end of the period	60,417	88,573	60,417	88,573
Reverse Loan
Servicing Asset at Amortized Cost, Balance [Roll Forward]
Balance at beginning of the period			5,505	7,258
Sales			0	0
Amortization of servicing rights	(400)	(400)	(782)	(906)
Balance at end of the period	$ 4,723	$ 6,352	$ 4,723	$ 6,352