Fair Value - Summary of Components of Net Fair Value Gains on Reverse Loans and Related HMBS Obligations (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Net fair value gains (losses) on reverse loans and related HMBS obligations
Interest income on reverse loans	$ 106,280	$ 96,881
Change in fair value of reverse loans	16,727	108,528
Net fair value gains on reverse loans	123,007	205,409
Interest expense on HMBS related obligations	(98,536)	(90,560)
Change in fair value of HMBS related obligations	6,303	(97,613)
Net fair value losses on HMBS related obligations	(92,233)	(188,173)
Net fair value gains on reverse loans and related HMBS obligations	$ 30,774	$ 17,236