Comprehensive Income Other Comprehensive Income (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Schedule of Comprehensive Income [Line Items]
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	$ 697	$ (1,208)	$ (2,961)
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	441	402	168
Other Comprehensive Income (Loss), before Tax	2,071	(1,329)	(4,547)
Other Comprehensive Income (Loss), Tax	(933)	523	1,754
Other Comprehensive Income (Loss)	1,138	(806)	(2,793)
Accumulated Net Unrealized Investment Gain (Loss) [Member]
Schedule of Comprehensive Income [Line Items]
Other Comprehensive Income (Loss), before Reclassifications, before Tax	(1,672)	(3,017)	356
Other Comprehensive Income Loss Before Reclassifications Tax (Expense) Benefit	648	1,185	(124)
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	(1,024)	(1,832)	232
Reclassification from Accumulated Other Comprehensive Income, Current Period, before Tax	22	(129)	(110)
Reclassification From Accumulated Other Comprehensive Income Current Period Tax (Expense) Benefit	(9)	51	43
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	13	(78)	(67)
Other Comprehensive Income (Loss)	(1,011)	(1,910)	165
Accumulated Defined Benefit Plans Adjustment, Net Unamortized Gain (Loss) [Member]
Schedule of Comprehensive Income [Line Items]
Other Comprehensive Income (Loss), before Reclassifications, before Tax	3,017	1,395	(4,610)
Other Comprehensive Income Loss Before Reclassifications Tax (Expense) Benefit	(1,296)	(547)	1,764
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	1,721	848	(2,846)
Reclassification from Accumulated Other Comprehensive Income, Current Period, before Tax	716	846	474
Reclassification From Accumulated Other Comprehensive Income Current Period Tax (Expense) Benefit	(281)	(332)	(186)
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	435	514	288
Other Comprehensive Income (Loss)	2,156	1,362	(2,558)
Accumulated Defined Benefit Plans Adjustment, Net Prior Service Cost (Credit) [Member]
Schedule of Comprehensive Income [Line Items]
Other Comprehensive Income (Loss), before Reclassifications, before Tax	0	(368)	(570)
Other Comprehensive Income Loss Before Reclassifications Tax (Expense) Benefit	0	144	223
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	0	(224)	(347)
Reclassification from Accumulated Other Comprehensive Income, Current Period, before Tax	(12)	(56)	(87)
Reclassification From Accumulated Other Comprehensive Income Current Period Tax (Expense) Benefit	5	22	34
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	(7)	(34)	(53)
Other Comprehensive Income (Loss)	$ (7)	$ (258)	$ (400)