Comprehensive Income Changes in Accumulated Other Comprehensive Income By Componenet (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated Other Comprehensive Loss	$ (7,166)	$ (4,373)	$ (8,462)	$ 6,695
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	(2,961)	3,500	(2,246)
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	168	589	479
Other Comprehensive (Loss) Income	(2,793)	4,089	(1,767)
Accumulated Net Unrealized Investment Gain (Loss) [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated Other Comprehensive Loss	2,539	2,374	5,625	6,808
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	232	(2,925)	(661)
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	(67)	(326)	(522)
Other Comprehensive (Loss) Income	165	(3,251)	(1,183)
Accumulated Defined Benefit Plans Adjustment, Net Unamortized Gain (Loss) [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated Other Comprehensive Loss	(9,255)	(6,697)	(14,036)	(13,709)
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	(2,846)	6,425	(1,340)
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	288	914	1,013
Other Comprehensive (Loss) Income	(2,558)	7,339	(327)
Accumulated Defined Benefit Plans Adjustment, Net Prior Service Cost (Credit) [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated Other Comprehensive Loss	(450)	(50)	(51)	206
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	(347)	0	(245)
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	(53)	1	(12)
Other Comprehensive (Loss) Income	$ (400)	$ 1	$ (257)