Comprehensive Income Other Comprehense Income (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Comprehensive Income [Abstract]
Net Unrealized Securities Holding Gains Arising During the Period, Before-Tax Amount	$ 739	$ 4,324	$ 577	$ 6,272
Net Unrealized Securities Holding Gain Arising During the Period, Tax (Expense) Benefit	(294)	(1,713)	(230)	(2,485)
Net Unrealized Securities Holding Gains Arising During the Period	445	2,611	347	3,787
Reclassification Adjustment for Securities Gains Included in Net Income, Before-Tax Amount	(143)	(482)	(645)	(1,024)
Reclassification Adjustment for Securities Gains Included in Net Income, Tax (Expense) Benefit	57	191	256	406
Reclassification Adjustment for Securities Gains Included in Net Income	(86)	(291)	(389)	(618)
Amortization of Net Retirement Plan Actuarial Loss, Before-Tax Amount	379	257	757	512
Amortization of Net Retirement Plan Actuarial Loss, Tax (Expense) Benefit	(150)	(102)	(300)	(203)
Amortization of Net Retirement Plan Actuarial Loss	229	155	457	309
Accretion of Net Retirement Plan Prior Service Credit, Before-Tax Amount	(8)	(32)	(15)	(63)
Accretion of Net Retirement Plan Prior Service Credit, Tax (Expense) Benefit	3	13	6	25
Accretion of Net Retirement Plan Prior Service Credit	(5)	(19)	(9)	(38)
Other Comprehensive Loss, Before-Tax Amount	967	4,067	674	5,697
Other Comprehensive Loss, Tax (Expense) Benefit	(384)	(1,611)	(268)	(2,257)
Other Comprehensive Loss, Net-of-Tax Amount	$ 583	$ 2,456	$ 406	$ 3,440