Consolidated Statements of Comprehensive Income (Unaudited) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Net income	$ 5,398	$ 5,263
Net unrealized losses on available-for-sale investment securities:
Less: reclassification adjustment for net gains on sales realized in net income	185	258
Less: reclassification adjustment for other-than-temporary impairment on equity securities realized in net income		(3)
Defined benefit pension plans:
Less: amortization of net loss included in net periodic pension costs	292	297
Less: accretion of prior service cost included in net periodic pension costs	(64)	(64)
Before Tax Amount
Net income	7,108	6,209
Net unrealized losses on available-for-sale investment securities:
Net unrealized holding losses arising during the period	(1,404)	(900)
Less: reclassification adjustment for net gains on sales realized in net income	(185)	(258)
Less: reclassification adjustment for other-than-temporary impairment on equity securities realized in net income		3
Total net unrealized losses on available-for-sale investment securities	(1,589)	(1,155)
Net change in fair value of derivatives used for cash flow hedges	162	174
Defined benefit pension plans:
Less: amortization of net loss included in net periodic pension costs	292	297
Less: accretion of prior service cost included in net periodic pension costs	(64)	(64)
Total defined benefit pension plans	228	233
Other comprehensive loss	(1,199)	(748)
Total comprehensive income	5,909	5,461
Tax Expense (Benefit)
Net income	1,710	946
Net unrealized losses on available-for-sale investment securities:
Net unrealized holding losses arising during the period	(491)	(315)
Less: reclassification adjustment for net gains on sales realized in net income	(65)	(90)
Less: reclassification adjustment for other-than-temporary impairment on equity securities realized in net income		1
Total net unrealized losses on available-for-sale investment securities	(556)	(404)
Net change in fair value of derivatives used for cash flow hedges	57	61
Defined benefit pension plans:
Less: amortization of net loss included in net periodic pension costs	102	104
Less: accretion of prior service cost included in net periodic pension costs	(23)	(23)
Total defined benefit pension plans	79	81
Other comprehensive loss	(420)	(262)
Total comprehensive income	1,290	684
Net of Tax Amount
Net income	5,398	5,263
Net unrealized losses on available-for-sale investment securities:
Net unrealized holding losses arising during the period	(913)	(585)
Less: reclassification adjustment for net gains on sales realized in net income	(120)	(168)
Less: reclassification adjustment for other-than-temporary impairment on equity securities realized in net income		2
Total net unrealized losses on available-for-sale investment securities	(1,033)	(751)
Net change in fair value of derivatives used for cash flow hedges	105	113
Defined benefit pension plans:
Less: amortization of net loss included in net periodic pension costs	190	193
Less: accretion of prior service cost included in net periodic pension costs	(41)	(41)
Total defined benefit pension plans	149	152
Other comprehensive loss	(779)	(486)
Total comprehensive income	$ 4,619	$ 4,777