Accumulated Other Comprehensive Income (Loss) (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012	Mar. 31, 2012
Equity [Abstract]
Net unrealized gain on securities available for sale, gross	$ 8,524	$ 9,451	$ 7,036
Net unrealized gain on securities available for sale, tax	3,180	3,525	2,624
Net unrealized gain on securities available for sale, net	5,344	5,926	4,412
Net unrealized loss on other-than-temporarily impaired securities available for sale, gross	(2,152)	(2,162)	(2,265)
Net unrealized loss on other-than-temporarily impaired securities available for sale, tax	(803)	(806)	(845)
Net unrealized loss on other-than-temporarily impaired securities available for sale, net	(1,349)	(1,356)	(1,420)
Net unamortized pension costs, gross	(2,396)	(2,484)	(1,728)
Net unamortized pension costs, tax	(894)	(927)	(644)
Net unamortized pension costs, net	(1,502)	(1,557)	(1,084)
Net unrealized loss on cash flow hedge, gross	(1,773)	(2,364)	(3,738)
Net unrealized loss on cash flow hedge, tax	(662)	(882)	(1,394)
Net unrealized (loss) gain on cash flow hedge, net	(1,111)	(1,482)	(2,344)
Accumulated other comprehensive income (loss), gross	2,203	2,441	(695)
Accumulated other comprehensive income (loss), tax	821	910	(259)
Accumulated other comprehensive income (loss), net	$ 1,382	$ 1,531	$ (436)