Accumulated Other Comprehensive Income (Loss) (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2017 USD ($)
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	$ (6,331)
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	1,270
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	(1,440)
Other Comprehensive Income (Loss), Available-for-sale Securities Adjustment, Net of Tax	1,025
Ending Balance	(5,153)
Accumulated Currency Translation [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(2,015)
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	1,270
Ending Balance	(745)
Accumulated Postretirement Transactions [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(4,731)
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	323
Ending Balance	(4,408)
Accumulated Net Investment Gain (Loss) Attributable to Parent [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	415
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	(1,440)
Other Comprehensive Income (Loss), Available-for-sale Securities Adjustment, Net of Tax	1,025
Ending Balance	0
Scenario, Previously Reported [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	$ 323