Comprehensive Income Changes in Accumulated Other Comprehensive Income By Component (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2015		Mar. 31, 2014		Dec. 31, 2014		Dec. 31, 2013
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated Other Comprehensive Loss	$ (6,256)	[1]	$ (4,075)	[1]	$ (7,166)	[1]	$ (4,373)	[1]
Other comprehensive income, before reclassifications, net of tax	745	[1]	241	[1]
Reclassification from Accumulated Other Comprehensive Income, net of tax	165	[1]	57	[1]
Other Comprehensive Income	910	[1]	298	[1]
Unrealized Gains and Losses on Available for Sale Securities [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated Other Comprehensive Loss	3,339	[1]	2,615	[1]	2,539	[1]	2,374	[1]
Other comprehensive income, before reclassifications, net of tax	745		241
Reclassification from Accumulated Other Comprehensive Income, net of tax	55		0
Other Comprehensive Income	800	[1]	241	[1]
Amortization of Net Retirement Plan Actuarial Loss [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated Other Comprehensive Loss	(9,138)	[1]	(6,627)	[1]	(9,255)	[1]	(6,697)	[1]
Other comprehensive income, before reclassifications, net of tax	0	[1]	0	[1]
Reclassification from Accumulated Other Comprehensive Income, net of tax	117		70
Other Comprehensive Income	117	[1]	70	[1]
Accretion of Net Retirement Plan Prior Service Credit [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated Other Comprehensive Loss	(457)	[1]	(63)	[1]	(450)	[1]	(50)	[1]
Other comprehensive income, before reclassifications, net of tax	0	[1]	0	[1]
Reclassification from Accumulated Other Comprehensive Income, net of tax	(7)		(13)
Other Comprehensive Income	$ (7)	[1]	$ (13)	[1]

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