Fair Values of Financial Instruments - Summary of Assets Measured at Fair Value on a Nonrecurring Basis (Detail) (Fair Value, Measurements, Nonrecurring, USD $) In Thousands, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Loans held for sale	$ 64,313	$ 103,396
Impaired loans	4,050	3,497
Other real estate owned	2,568	2,735
Total	70,931	109,628
Significant Unobservable Inputs (Level3) [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Loans held for sale	64,313	103,396
Impaired loans	4,050	3,497
Other real estate owned	2,568	2,735
Total	$ 70,931	$ 109,628