Changes in Residential and Participation Mortgage Servicing Rights (Detail) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Finite-Lived Intangible Assets [Line Items]
Carrying value, beginning of period				$ 247,734
Carrying value, end of period		$ 197,195		197,195
Mortgage Servicing Rights Residential
Finite-Lived Intangible Assets [Line Items]
Carrying value, beginning of period		188,331	$ 250,963	243,389	$ 227,297
Additions		12,005	9,219	31,185	40,217
Due to changes in interest rates		5,668	(15,703)	(32,139)	(844)
Due to model assumption changes	[1]		(1,506)	(13,088)	(1,506)
Due to loan payoffs		(12,818)	(9,023)	(31,939)	(29,502)
Due to passage of time and other changes		(1,767)	(1,528)	(5,989)	(3,240)
Carrying value, end of period		191,419	232,422	191,419	232,422
Mortgage Servicing Rights Participation
Finite-Lived Intangible Assets [Line Items]
Carrying value, beginning of period		5,663	2,675	4,345
Additions		731	1,350	2,999	4,178
Amortization		(618)	(229)	(1,568)	(382)
Carrying value, end of period		$ 5,776	$ 3,796	$ 5,776	$ 3,796

[1] Represents changes in fair value driven by changes to the inputs to the valuation model related to assumed prepayment speeds.