Comprehensive Income Reclassification out of Accumulated Other Comprehensive Income (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013		Mar. 31, 2012
Reclassification out of Accumulated Other Comprehensive Income [Line Items]
Total Before Tax	$ 7,420		$ 7,539
Provision for Income Taxes	2,239		2,251
Net Income	5,181		5,288
Total Reclassifications for the period, net of tax	82		79
Reclassification out of Accumulated Other Comprehensive Income [Member] | Unrealized Gains and Losses on Available for Sale Securities [Member]
Reclassification out of Accumulated Other Comprehensive Income [Line Items]
Reclassification Adjustment for Securities Gains Included in Net Income, Before-Tax Amount	527		502
Total Before Tax	527		502
Provision for Income Taxes	(209)		(199)
Net Income	318		303
Reclassification out of Accumulated Other Comprehensive Income [Member] | Accumulated Defined Benefit Plans Adjustment [Member]
Reclassification out of Accumulated Other Comprehensive Income [Line Items]
Amortization of Defined Benefit Pension Items, Prior-Service Costs, Before Tax	0	[1]	7	[1]
Amortization of Net Retirement Plan Actuarial Loss, Before-Tax Amount	(391)	[1]	(378)	[1]
Total Before Tax	(391)		(371)
Provision for Income Taxes	155		147
Net Income	$ (236)		$ (224)

[1] (2) These accumulated other comprehensive income components are included in the computation of net periodic pension cost (see pension footnote for additional details.).