Comprehensive Income Other Comprehensive Income (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Other Comprehensive Income (Loss), Net of Tax [Abstract]
Unrealized Securities Holding Gains Arising During the Period, Before-Tax Amount	$ (1,094)	$ 7,850	$ 2,507
Unrealized Securities Holding Gains During the Period, Tax (Expense) Benefit	433	(3,109)	(993)
Unrealized Securities Holding (Losses) Gains Arising During the Period	(661)	4,741	1,514
Reclassification Adjustment for Net Securities Gains Included in Net Income, Before-Tax Amount	(865)	(2,795)	(1,507)
Reclassification Adjustment for Net Securities Gains Included in Net Income, Tax (Expense) Benefit	343	1,107	597
Reclassification Adjustment for Net Securities Gains Included in Net Income, Net of Tax	(522)	(1,688)	(910)
Net Retirement Plan Loss, Before-Tax Amount	(2,218)	(6,129)	(1,811)
Net Retirement Plan Loss, Tax (Expense) Benefit	878	2,428	718
Net Retirement Plan Loss	(1,340)	(3,701)	(1,093)
Net Retirement Plan Prior Service Credit, Before-Tax Amount	(405)	(266)	242
Net Retirement Plan Prior Service Cost, Tax (Expense) Benefit	160	105	(96)
Net Retirement Plan Prior Service (Cost) Credit, Net of Tax	(245)	(161)	146
Amortization of Net Retirement Plan Actuarial Loss, Before-Tax Amount	1,677	996	1,112
Amortization of Net Retirement Plan Actuarial Loss, Tax (Expense) Benefit	(664)	(394)	(440)
Amortization of Net Retirement Plan Actuarial Loss, Net of Tax	1,013	602	672
Accretion of Net Retirement Plan Prior Service Credit, Before-Tax Amount	(20)	(108)	(186)
Accretion of Net Retirement Plan Prior Service Credit, Tax (Expense) Benefit	8	43	74
Accretion of Net Retirement Plan Prior Service Credit, Net of Tax	(12)	(65)	(112)
Other Comprehensive Income (Loss), Before-Tax Amount	(2,925)	(452)	357
Other Comprehensive Income, Tax (Expense) Benefit	1,158	180	(140)
Other Comprehensive (Loss) Income	$ (1,767)	$ (272)	$ 217