Consolidated Statements Of Comprehensive Income (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Consolidated Statements of Comprehensive Income [Abstract]
Net Income	$ 23,428	$ 26,177	$ 24,766
Unrealized gains on available for sale securities:
Unrealized holding gains (losses) on available for sale arising during period, net of related tax effects of $(1,851), $(3,365), and $594	3,439	6,248	(1,120)
Reclassification adjustment for (gains) losses included in net income, net of related tax effects of $874, $727, and $(143)	(1,624)	(1,349)	266
Net change in unrealized gains on available for sale securities	1,815	4,899	(854)
Unrealized gain (loss) on cash flow hedging derivatives, net of related tax effects of $(32), $3,530, and $779	59	(6,555)	(1,448)
Postretirement plans:
Net actuarial loss arising during period, net of related tax effects of $511, $336, and $132	(950)	(624)	(247)
Reclassification of amortization of prior service cost included in net periodic cost, net of related tax effects of $(7), $(7), and $(6)	12	12	13
Other comprehensive income (loss)	936	(2,268)	(2,536)
Comprehensive Income	$ 24,364	$ 23,909	$ 22,230