Comprehensive Income - Components of Accumulated Other Comprehensive Income (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Equity [Abstract]
Net unrealized gains on available-for-sale securities	$ 4,202	$ 8,434
Tax effect	(1,767)	(3,547)
Unrealized holding gains on available-for-sale securities, net of tax	2,435	4,887
Unfunded status of the supplemental retirement plans	(787)	(3,806)
Tax effect	331	1,600
Unfunded status of the supplemental retirement plans, net of tax	(456)	(2,206)	(2,204)
Joint beneficiary agreement liability	(122)	(522)
Tax effect
Joint beneficiary agreement liability, net of tax	(122)	(522)
Accumulated other comprehensive income	$ 1,857	$ 2,159