Accumulated Other Comprehensive Income (Loss) (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011	Sep. 30, 2011
Accumulated Other Comprehensive Income (Loss) [Abstract]
Net unrealized gain on securities available for sale, gross	$ 10,484	$ 7,202	$ 8,350
Net unrealized gain on securities available for sale, tax	3,910	2,688	3,115
Net unrealized gain on securities available for sale, net	6,574	4,514	5,235
Net unrealized loss on other-than-temporarily impaired securities available for sale, gross	(2,253)	(2,318)	(2,457)
Net unrealized loss on other-than-temporarily impaired securities available for sale, tax	(840)	(865)	(916)
Net unrealized loss on other-than-temporarily impaired securities available for sale, net	(1,413)	(1,453)	(1,541)
Net unamortized pension costs, gross	(2,670)	(4,272)	(2,208)
Net unamortized pension costs, tax	(996)	(1,593)	(824)
Net unamortized pension costs, net	(1,674)	(2,679)	(1,384)
Net unrealized loss on cash flow hedge, gross	(2,653)	(1,834)	(1,729)
Net unrealized loss on cash flow hedge, tax	(990)	(684)	(645)
Net unrealized (loss) gain on cash flow hedge, net	(1,663)	(1,150)	(1,084)
Accumulated other comprehensive income (loss), gross	2,908	(1,222)	1,956
Accumulated other comprehensive income (loss), tax	1,084	(454)	730
Accumulated other comprehensive income (loss), net	$ 1,824	$ (768)	$ 1,226