Comprehensive Income Changes in Accumulated Other Comprehensive Income By Component (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended				9 Months Ended
	Sep. 30, 2013		Sep. 30, 2012		Sep. 30, 2013		Sep. 30, 2012
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Accumulated Other Comprehensive Income (Loss), Net of Tax, Beginning of Period	$ (11,739)	[1]	$ (6,289)	[1]	$ (8,462)	[1]	$ (6,695)	[1]
Other comprehensive income (loss), before reclassifications, net of tax	1,210	[1]	411	[1]	(2,213)	[1]	758	[1]
Reclassification from Accumulated Other Comprehensive Income, current period, net of tax	236	[1]	185	[1]	382	[1]	244	[1]
Other Comprehensive (Loss) Income	1,446	[1]	596	[1]	(1,831)	[1]	1,002	[1]
Accumulated Other Comprehensive Income (Loss), Net of Tax, End of Period	(10,293)	[1]	(5,693)	[1]	(10,293)	[1]	(5,693)	[1]
Unrealized Gains and Losses on Available for Sale Securities [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Accumulated Other Comprehensive Income (Loss), Net of Tax, Beginning of Period	1,876	[1]	6,766	[1]	5,625	[1]	6,808	[1]
Other comprehensive income (loss), before reclassifications, net of tax	1,210	[1]	411	[1]	(2,213)	[1]	758	[1]
Reclassification from Accumulated Other Comprehensive Income, current period, net of tax	0	[1]	(39)	[1]	(326)	[1]	(428)	[1]
Other Comprehensive (Loss) Income	1,210	[1]	372	[1]	(2,539)	[1]	330	[1]
Accumulated Other Comprehensive Income (Loss), Net of Tax, End of Period	3,086	[1]	7,138	[1]	3,086	[1]	7,138	[1]
Amortization of Net Retirement Plan Actuarial Loss [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Accumulated Other Comprehensive Income (Loss), Net of Tax, Beginning of Period	(13,564)	[1]	(13,252)	[1]	(14,036)	[1]	(13,709)	[1]
Other comprehensive income (loss), before reclassifications, net of tax	0	[1]	0	[1]	0	[1]	0	[1]
Reclassification from Accumulated Other Comprehensive Income, current period, net of tax	235	[1]	228	[1]	707	[1]	685	[1]
Other Comprehensive (Loss) Income	235	[1]	228	[1]	707	[1]	685	[1]
Accumulated Other Comprehensive Income (Loss), Net of Tax, End of Period	(13,329)	[1]	(13,024)	[1]	(13,329)	[1]	(13,024)	[1]
Accretion of Net Retirement Plan Prior Service Credit [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Accumulated Other Comprehensive Income (Loss), Net of Tax, Beginning of Period	(51)	[1]	197	[1]	(51)	[1]	206	[1]
Other comprehensive income (loss), before reclassifications, net of tax	0	[1]	0	[1]	0	[1]	0	[1]
Reclassification from Accumulated Other Comprehensive Income, current period, net of tax	1	[1]	(4)	[1]	1	[1]	(13)	[1]
Other Comprehensive (Loss) Income	1	[1]	(4)	[1]	1	[1]	(13)	[1]
Accumulated Other Comprehensive Income (Loss), Net of Tax, End of Period	$ (50)	[1]	$ 193	[1]	$ (50)	[1]	$ 193	[1]

[1] (1) All amounts are net of tax. Amounts in parentheses indicate debits.