Comprehensive Income - Components of Other Comprehensive Income and Related Tax Effects (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Equity [Abstract]
Unrealized holding (losses) gains on available for sale securities before reclassifications	$ (4,232)	$ (2,096)	$ 2,594
Amounts reclassified out of accumulated other comprehensive income
Unrealized holding (losses) gains on available for sale securities after reclassifications	(4,232)	(2,096)	2,594
Tax effect	1,780	880	(1,090)
Unrealized holding (losses) gains on available-for-sale securities, net of tax	(2,452)	(1,216)	1,504
Change in unfunded status of the supplemental retirement plans before reclassifications	2,575	(4,445)	1,429
Amortization of prior service cost	153	153	153
Amortization of actuarial losses	291	288	386
Total amounts reclassified out of accumulated other comprehensive income	444	441	539
Change in unfunded status of the supplemental retirement plans after reclassifications	3,019	(4)	1,968
Tax effect	(1,269)	2	(828)
Change in unfunded status of the supplemental retirement plans, net of tax	1,750	(2)	1,140
Change in joint beneficiary agreement liability before reclassifications	400	(370)	(248)
Amounts reclassified out of accumulated other comprehensive income
Change in joint beneficiary agreement liability after reclassifications	400	(370)	(248)
Tax effect	0	(64)	105
Change in joint beneficiary agreement liability, net of tax	400	(434)	(143)
Total other comprehensive (loss) income	$ (302)	$ (1,652)	$ 2,501