Fair Value - Summary of Components of Net Fair Value Gains on Reverse Loans and Related HMBS Obligations (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Net fair value gains (losses) on reverse loans and related HMBS obligations
Interest income on reverse loans	$ 109,406	$ 98,258	$ 215,686	$ 195,139
Change in fair value of reverse loans	(40,228)	(8,687)	(23,501)	99,841
Net fair value gains on reverse loans	69,178	89,571	192,185	294,980
Interest expense on HMBS related obligations	(100,564)	(91,470)	(199,100)	(182,030)
Change in fair value of HMBS related obligations	38,201	28,835	44,504	(68,778)
Net fair value losses on HMBS related obligations	(62,363)	(62,635)	(154,596)	(250,808)
Net fair value gains on reverse loans and related HMBS obligations	$ 6,815	$ 26,936	$ 37,589	$ 44,172