Servicing of Residential Loans - Summary of Activity in Carrying Value of Servicing Rights (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Servicing Asset at Amortized Cost, Balance [Roll Forward]
Amortization of servicing rights	$ (7,013)	$ (11,117)
Forward Loans [Member]
Servicing Asset at Amortized Cost, Balance [Roll Forward]
Balance at beginning of the period	121,364	161,782
Amortization of servicing rights	(6,458)	(10,367)
Balance at end of the period	114,906	151,415
Reverse Loans [Member]
Servicing Asset at Amortized Cost, Balance [Roll Forward]
Balance at beginning of the period	9,311	11,994
Amortization of servicing rights	(555)	(750)
Balance at end of the period	$ 8,756	$ 11,244