Fair Value Measurement - Reconciliation of Assets and Liabilities Measured at Fair Value Using Significant Unobservable Inputs (Level 3) on Recurring Basis (Detail) (Mortgage servicing rights [Member], USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Mortgage servicing rights [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance	$ 7,378	$ 6,165
Transfers into (out of) Level 3	0	0
Change Included in Earnings	(506)	(181)
Issuances	185	123
Ending Balance	$ 7,057	$ 6,107