Consolidated Statements Of Comprehensive Income - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Statement of Comprehensive Income [Abstract]
Net income		$ 20,952	$ 24,570	$ 22,783
Net change in unrealized gains (losses) on available-for-sale securities:
Net change in unrealized gain (loss) on available-for-sale securities, net of tax of $1,873, ($4,275), and $10,982, respectively		(3,479)	7,938	(20,397)
Net reclassification adjustment for gains included in net income, net of tax of $1, $158, and $275, respectively	[1]	(3)	(293)	(510)
Net change in unrealized gains (losses) on available-for-sale securities, net of tax		(3,482)	7,645	(20,907)
Net change in unrealized gains (losses) on cash flow hedging derivatives:
Net change in unrealized gain (loss) on cash flow hedging derivatives, net of tax of $825, $2,431, and ($1,947), respectively		(1,533)	(4,515)	3,616
Net reclassification adjustment for effective portion of cash flow hedges included in interest expense, net of tax of ($593), ($600), and ($564), respectively	[2]	1,102	1,114	1,047
Net change in unrealized gains (losses) on cash flow hedging derivatives, net of tax of $232, $1,831, and ($2,510), respectively		(431)	(3,401)	4,663
Postretirement plans:
Net actuarial (loss) gain, net of tax of $21, $225, and ($391), respectively		(39)	(418)	726
Reclassification of amortization of net unrecognized actuarial loss and of prior service cost included in net periodic cost, net of tax of ($84), ($51), and ($94), respectively	[3]	155	96	174
Net gain (loss) on postretirement plans, net of tax		116	(322)	900
Other comprehensive income (loss)		(3,797)	3,922	(15,344)
Comprehensive income		$ 17,155	$ 28,492	$ 7,439

[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 interest on subordinated debentures.

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