Consolidated Statements of Comprehensive Income (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Statement of Comprehensive Income [Abstract]
Income, Before Tax Amount	$ 8,499	$ 7,439	$ 22,857	$ 20,914
Net unrealized gains (losses) on available-for-sale investment securities, Before Tax Amount
Net unrealized holding gains (losses) arising during the period, Before Tax Amount	(486)	442	4,972	(10,163)
Less: reclassification adjustment for net gains on sales realized in net income, Before Tax Amount	0	(1,426)	(557)	(2,950)
Total net unrealized gains (losses) on available-for-sale investment securities, Before Tax Amount	(486)	(984)	4,415	(13,113)
Cash flow hedge derivative, Before Tax Amount
Net change in fair value of interest rate swap, Before Tax Amount			0	43
Less: reclassification adjustment for loss on termination of interest rate swap realized in net income, Before Tax Amount			0	1,866
Total cash flow hedge derivative, Before Tax Amount			0	1,909
Defined benefit pension plans, Before Tax Amount
Less: amortization of net actuarial loss included in net periodic pension costs, Before Tax Amount	168	320	499	961
Less: accretion of prior service cost included in net periodic pension costs, Before Tax Amount	(72)	(64)	(216)	(191)
Total defined benefit pension plans, Before Tax Amount	96	256	283	770
Other comprehensive income (loss), Before Tax Amount	(390)	(728)	4,698	(10,434)
Total comprehensive income (loss), Before Tax Amount	8,109	6,711	27,555	10,480
Tax (expense) benefit	2,264	1,400	5,816	4,647
Net unrealized gains (losses) on available-for-sale investment securities, Tax Expense (Benefit)
Net unrealized holding gains (losses) arising during the period, Tax Expense (Benefit)	(170)	155	1,741	(3,557)
Less: reclassification adjustment for net gains on sales realized in net income, Tax Expense (Benefit)	0	(499)	(195)	(1,032)
Total net unrealized gains (losses) on available-for-sale investment securities, Tax Expense (Benefit)	(170)	(344)	1,546	(4,589)
Cash flow hedge derivative, Tax Expense (Benefit)
Net change in fair value of interest rate swap, Tax Expense (Benefit)			0	15
Less: reclassification adjustment for loss on termination of interest rate swap realized in net income, Tax Expense (Benefit)			0	653
Total cash flow hedge derivative, Tax Expense (Benefit)			0	668
Defined benefit pension plans, Tax Expense (Benefit)
Less: amortization of net actuarial loss included in net periodic pension costs, Tax Expense (Benefit)	59	112	175	336
Less: accretion of prior service cost included in net periodic pension costs, Tax Expense (Benefit)	(26)	(22)	(77)	(66)
Total defined benefit pension plans, Tax Expense (Benefit)	33	90	98	270
Other comprehensive income (loss), Tax Expense (Benefit)	(137)	(254)	1,644	(3,651)
Total comprehensive income (loss), Tax Expense (Benefit)	2,127	1,146	7,460	996
Income, Net of Tax Amount	6,235	6,039	17,041	16,267
Net unrealized gains (losses) on available-for-sale investment securities, Net of Tax Amount
Net unrealized holding gains (losses) arising during the period, Net of Tax Amount	(316)	287	3,231	(6,606)
Less: reclassification adjustment for net gains on sales realized in net income, Net of Tax Amount	0	(927)	(362)	(1,918)
Total net unrealized gains (losses) on available-for-sale investment securities, Net of Tax Amount	(316)	(640)	2,869	(8,524)
Cash flow hedge derivative, Net of Tax Amount
Net change in fair value of interest rate swap, Net of Tax Amount			0	28
Less: reclassification adjustment for loss on termination of interest rate swap realized in net income, Net of Tax Amount			0	1,213
Total cash flow hedge derivative, Net of Tax Amount			0	1,241
Defined benefit pension plans, Net of Tax Amount
Less: amortization of net actuarial loss included in net periodic pension costs, Net of Tax Amount	109	208	324	625
Less: accretion of prior service cost included in net periodic pension costs, Net of Tax Amount	(46)	(42)	(139)	(125)
Total defined benefit pension plans, Net of Tax Amount	63	166	185	500
Other comprehensive income (loss), Net of Tax Amount	(253)	(474)	3,054	(6,783)
Total comprehensive income (loss), Net of Tax Amount	$ 5,982	$ 5,565	$ 20,095	$ 9,484