Consolidated Statements Of Comprehensive Income (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
Statement of Comprehensive Income [Abstract]
Net Income	$ 24,570		$ 22,783		$ 23,428
Unrealized gains on available for sale securities:
Net change in unrealized gain (loss) on available-for-sale securities, net of tax of $(4,275), $10,982, and $(1,851), respectively	7,938		(20,397)		3,439
Net reclassification adjustment for gains included in net income, net of tax of $158, $275, and $874, respectively	(293)	[1]	(510)	[1]	(1,624)	[1]
Net change in unrealized gains (losses) on available-for-sale securities, net of tax	7,645		(20,907)		1,815
Net change in unrealized gains (losses) on cash flow hedging derivatives, net of tax of $1,831, $(2,510), and $(32), respectively	(3,401)		4,663		59
Postretirement plans:
Net actuarial (loss) gain, net of tax of $225, $(391), and $563, respectively	(418)		726		(1,046)
Reclassification of amortization of net unrecognized actuarial loss and of prior service cost included in net periodic cost, net of tax of $(51), $(94), and $(56), respectively	96	[2]	174	[2]	108	[2]
Net gain (loss) on postretirement plans, net of tax	(322)		900		(938)
Other comprehensive income (loss)	3,922		(15,344)		936
Comprehensive Income	$ 28,492		$ 7,439		$ 24,364

[1] (1) Reclassified into the consolidated statements of income in net gain on sale of securities.

[2] (2) Reclassified into the consolidated statements of income in salaries and employee benefits.