Consolidated Statements of Comprehensive Income (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Net Income	$ 5,181	$ 5,288
Other comprehensive income (loss), before reclassifications, net of tax	220	(98)
Reclassification from Accumulated Other Comprehensive Income, current period, net of tax	(82)	(79)
Other Comprehensive Income (Loss)	138	(177)
Comprehensive Income	5,319	5,111
Unrealized Gains and Losses on Available for Sale Securities [Member]
Other comprehensive income (loss), before reclassifications, net of tax	220	(98)
Reclassification from Accumulated Other Comprehensive Income, current period, net of tax	(318)	(303)
Amortization of Net Retirement Plan Actuarial Loss [Member]
Other comprehensive income (loss), before reclassifications, net of tax	0	0
Reclassification from Accumulated Other Comprehensive Income, current period, net of tax	236	228
Accretion of Net Retirement Plan Prior Service Credit [Member]
Other comprehensive income (loss), before reclassifications, net of tax	0	0
Reclassification from Accumulated Other Comprehensive Income, current period, net of tax	$ 0	$ (4)