Capitalized Servicing Assets - Changes in Capitalized Servicing Assets (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Servicing Asset at Amortized Cost [Line Items]
Amortized value, Beginning balance	$ 186,917	$ 210,101	$ 172,976
Originations	65,470	44,207	79,129
Purchases	243	1,019	272
Recognized in loan securitization transactions			23,078
Amortization	(49,906)	(68,410)	(65,354)
Amortized value, ending balance	202,724	186,917	210,101
Valuation allowance			(300)
Ending balance, net	202,724	186,917	209,801
Other [Member]
Servicing Asset at Amortized Cost [Line Items]
Amortized value, Beginning balance	4,107	11,225	8,143
Recognized in loan securitization transactions			9,382
Amortization	(3,378)	(7,118)	(6,300)
Amortized value, ending balance	729	4,107	11,225
Ending balance, net	729	4,107	11,225
Residential Mortgage Loans [Member]
Servicing Asset at Amortized Cost [Line Items]
Amortized value, Beginning balance	109,871	126,377	104,855
Originations	35,556	28,285	52,375
Purchases	243	289	272
Recognized in loan securitization transactions			13,696
Amortization	(27,367)	(45,080)	(44,821)
Amortized value, ending balance	118,303	109,871	126,377
Valuation allowance			(300)
Ending balance, net	118,303	109,871	126,077
Commercial Mortgage Loans [Member]
Servicing Asset at Amortized Cost [Line Items]
Amortized value, Beginning balance	72,939	72,499	59,978
Originations	29,914	15,922	26,754
Purchases		730
Amortization	(19,161)	(16,212)	(14,233)
Amortized value, ending balance	83,692	72,939	72,499
Ending balance, net	$ 83,692	$ 72,939	$ 72,499