Derivative Financial Instruments - Impact of Derivatives on Consolidated Balance Sheet (Detail) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Derivatives, Fair Value [Line Items]
Derivative Assets	$ 15,314	$ 5,238
Gross position	(30,497)	(28,688)
Interest Rate Swaps
Derivatives, Fair Value [Line Items]
Derivative Assets	15,314	5,238
Gross position	(30,497)	(28,688)
Total net derivatives	(15,183)	(23,450)
Trading | Interest Rate Swaps
Derivatives, Fair Value [Line Items]
Derivative Assets	83	226
Gross position	(646)	(1,370)
Total net derivatives	(563)	(1,144)
Cash Flow | Interest Rate Swaps
Derivatives, Fair Value [Line Items]
Derivative Assets	0	0
Gross position	(27,512)	(21,435)
Total net derivatives	(27,512)	(21,435)
Fair Value | Interest Rate Swaps
Derivatives, Fair Value [Line Items]
Derivative Assets	15,231	5,012
Gross position	(2,339)	(5,883)
Total net derivatives	$ 12,892	$ (871)