Consolidated Statement of Comprehensive Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Net Income	$ 24,662	$ 23,360	$ 21,795
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	(1,208)	(2,961)	3,500
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	402	168	589
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	(806)	(2,793)	4,089
Comprehensive Income (Loss), Net of Tax	23,856	20,567	25,884
Accumulated Net Unrealized Investment Gain (Loss) [Member]
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	(1,832)	232	(2,925)
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	(78)	(67)	(326)
Accumulated Defined Benefit Plans Adjustment, Net Unamortized Gain (Loss) [Member]
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	848	(2,846)	6,425
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	514	288	914
Accumulated Defined Benefit Plans Adjustment, Net Prior Service Cost (Credit) [Member]
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	(224)	(347)	0
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	$ (34)	$ (53)	$ 1