Changes in Residential and Participation Mortgage Servicing Rights (Detail) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Finite-Lived Intangible Assets [Line Items]
Carrying value, beginning of period				$ 247,734
Carrying value, end of period		$ 193,994		193,994
Mortgage Servicing Rights Residential
Finite-Lived Intangible Assets [Line Items]
Carrying value, beginning of period		208,087	$ 220,371	243,389	$ 227,297
Additions		11,232	15,981	19,180	30,998
Due to changes in interest rates		(13,521)	25,957	(37,807)	14,859
Due to model assumption changes	[1]	(4,250)		(13,088)
Due to loan payoffs		(10,371)	(10,263)	(19,121)	(20,479)
Due to passage of time and other changes		(2,846)	(1,083)	(4,222)	(1,712)
Carrying value, end of period		188,331	250,963	188,331	250,963
Mortgage Servicing Rights Participation
Finite-Lived Intangible Assets [Line Items]
Carrying value, beginning of period		5,181		4,345
Additions		1,018	2,828	2,268	2,828
Amortization		(536)	(153)	(950)	(153)
Carrying value, end of period		$ 5,663	$ 2,675	$ 5,663	$ 2,675

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