Accumulated Other Comprehensive Income (Loss) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	$ 48,603	$ 65,602
Other comprehensive income (loss) before reclassification	(9,931)	(1,904)
Amounts reclassified from accumulated other comprehensive income	790	1,391
Income tax (expense) benefit	3,529	189
Net other comprehensive income (loss) during period	(5,612)	(324)
Ending Balance	42,991	65,278
Securities Available For Sale [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	86,109	99,761
Other comprehensive income (loss) before reclassification	(9,931)	(1,914)
Amounts reclassified from accumulated other comprehensive income	(300)	(40)
Income tax (expense) benefit	3,950	762
Net other comprehensive income (loss) during period	(6,281)	(1,192)
Ending Balance	79,828	98,569
Defined Benefit Plans [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(37,506)	(33,173)
Other comprehensive income (loss) before reclassification	0	0
Amounts reclassified from accumulated other comprehensive income	1,090	700
Income tax (expense) benefit	(421)	(273)
Net other comprehensive income (loss) during period	669	427
Ending Balance	(36,837)	(32,746)
Derivatives [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	0	(986)
Other comprehensive income (loss) before reclassification	0	10
Amounts reclassified from accumulated other comprehensive income	0	731
Income tax (expense) benefit	0	(300)
Net other comprehensive income (loss) during period	0	441
Ending Balance	$ 0	$ (545)