Accumulated Other Comprehensive Income (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Other Comprehensive Loss, Before Tax:
Net Unrealized Losses Arising During the Period	$ (12,595)	$ (6,586)
Less: Reclassification Adjustment for Gains Realized in Net Income	(3,307)	(4,024)
Net Unrealized Losses on Investment Securities	(15,902)	(10,610)
Net Actuarial Losses Arising During the Period	(206)
Amortization of Accumulated Benefit Plan Losses	414	332
Amortization of Prior Service Credit Included in Net Periodic Benefit Cost	(80)	(81)
Defined Benefit Plans, Net	128	251
Other Comprehensive Loss	(15,774)	(10,359)
Other Comprehensive Loss, Tax Effect:
Net Unrealized Losses Arising During the Period	(4,957)	(2,590)
Less: Reclassification Adjustment for Gains Realized in Net Income	(1,304)	(1,566)
Net Unrealized Losses on Investment Securities	(6,261)	(4,156)
Net Actuarial Losses Arising During the Period	(81)
Amortization of Accumulated Benefit Plan Losses	163	130
Amortization of Prior Service Included in Net Periodic Benefit Cost	(32)	(32)
Defined Benefit Plans, Net	50	98
Other Comprehensive Loss	(6,211)	(4,058)
Other Comprehensive Loss, Net of Tax:
Net Unrealized Losses Arising During the Period	(7,638)	(3,996)
Less: Reclassification Adjustment for Gains Realized in Net Income	(2,003)	(2,458)
Net Unrealized Losses on Investment Securities, Net of Tax	(9,641)	(6,454)
Net Actuarial Losses Arising During the Period	(125)
Amortization of Accumulated Benefit Plan Losses	251	202
Amortization of Prior Service Credit Included in Net Periodic Benefit Cost	(48)	(49)
Defined Benefit Plans, Net	78	153
Total Other Comprehensive Loss	$ (9,563)	$ (6,301)