Comprehensive Income - Components of Other Comprehensive Income (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Net unrealized gains (losses) on available for sale securities
Net unrealized holding gains (losses) arising during period, Before tax amount	$ 1,765	$ 1,933	$ (8,635)	$ 3,441
Reclassification adjustment for net gains arising during the period, Before tax amount			(506)	(273)
Net unrealized gains (losses), Before tax amount	1,765	1,933	(9,141)	3,168
Change in minimum pension liability, Before tax amount	8	8	23	23
Other comprehensive income (loss), net, Before tax amount	1,773	1,941	(9,118)	3,191
Net unrealized holding gains (losses) arising during period, Tax Benefit (Expense)	(647)	(713)	3,181	(1,267)
Reclassification adjustment for net gains arising during the period, Tax Benefit (Expense)			177	96
Net unrealized gains (losses), Tax Benefit (Expense)	(647)	(713)	3,358	(1,171)
Change in minimum pension liability, Tax Benefit (Expense)	(3)	(3)	(8)	(8)
Other comprehensive income (loss), net, Tax Benefit (Expense)	(650)	(716)	3,350	(1,179)
Net unrealized holding gains (losses) arising during period, Net of tax amount	1,118	1,220	(5,454)	2,174
Reclassification adjustment for net gains arising during the period, Net of tax amount	0	0	(329)	(177)
Net unrealized gains (losses), Net of tax amount	1,118	1,220	(5,783)	1,997
Change in minimum pension liability, Net of tax amount	5	5	15	15
Other Comprehensive Income (Loss)	$ 1,123	$ 1,225	$ (5,768)	$ 2,012