Derivative Financial Instruments - Impact of Derivatives on Consolidated Balance Sheet (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014		Dec. 31, 2013
Derivatives, Fair Value [Line Items]
Derivative Assets	$ 5,238		$ 6,761
Gross position	(28,688)		(6,149)
Interest Rate Swaps
Derivatives, Fair Value [Line Items]
Derivative Assets	5,238	[1]	6,761	[1]
Gross position	(28,688)	[1]	(6,149)	[1]
Total net derivatives	(23,450)		612
Trading | Interest Rate Swaps
Derivatives, Fair Value [Line Items]
Derivative Assets	226	[1]	426	[1]
Gross position	(1,370)	[1]	0	[1]
Total net derivatives	(1,144)		426
Cash Flow | Interest Rate Swaps
Derivatives, Fair Value [Line Items]
Derivative Assets	0	[1]	0	[1]
Gross position	(21,435)	[1]	0	[1]
Total net derivatives	(21,435)		0
Fair Value | Interest Rate Swaps
Derivatives, Fair Value [Line Items]
Derivative Assets	5,012	[1],[2]	6,335	[1],[2]
Gross position	(5,883)	[1],[2]	(6,149)	[1],[2]
Total net derivatives	$ (871)	[2]	$ 186	[2]

[1] The following table reconciles gross positions with the impact of master netting agreements to the balance sheet classification:

[2] Fair values reported are exclusive of collateral held and pledged and accrued interest. Assets and liabilities are presented without consideration of master netting agreements. Derivatives are carried on the balance sheet based on net position by counterparty under master netting agreements, and classified in other assets or other liabilities depending on whether in a net positive or negative position.