Accumulated Other Comprehensive Income (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated Other Comprehensive Income (Loss), Net of Tax		$ (6,295)	$ 5,621	$ (12,044)	$ 20,149
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax		(11,123)	17,922	(32,159)
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	[1]	(793)	(257)	(34)
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent		(11,916)	17,665	(32,193)
Accumulated Net Unrealized Investment Gain (Loss) [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated Other Comprehensive Income (Loss), Net of Tax		386	7,462	(10,108)	20,918
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax		(6,069)	17,922	(30,727)
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	[1]	(1,007)	(352)	(299)
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent		(7,076)	17,570	(31,026)
Accumulated Defined Benefit Plans Adjustment [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated Other Comprehensive Income (Loss), Net of Tax		(6,681)	(1,841)	(1,936)	$ (769)
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax		(5,054)	0	(1,432)
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	[1]	214	95	265
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent		$ (4,840)	$ 95	$ (1,167)

[1] (2) See following table for details about these reclassifications.