Comprehensive Income Reclassification out of Accumulated Other Comprehensive Income (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Reclassification out of Accumulated Other Comprehensive Income [Line Items]
Provision for income taxes	$ 2,150	$ 2,058
Net Income	(163)	45
Reclassification out of Accumulated Other Comprehensive Income | Accretion of Net Retirement Plan Prior Service (Cost) Credit
Reclassification out of Accumulated Other Comprehensive Income [Line Items]
Other nonoperating income (expense)	(56)	(1)
Reclassification out of Accumulated Other Comprehensive Income | Amortization of Net Retirement Plan Actuarial Gain (Loss)
Reclassification out of Accumulated Other Comprehensive Income [Line Items]
Other nonoperating income (expense)	(163)	60
Reclassification out of Accumulated Other Comprehensive Income | Accumulated Defined Benefit Plans Adjustment
Reclassification out of Accumulated Other Comprehensive Income [Line Items]
Total before tax	(219)	59
Provision for income taxes	56	(14)
Net Income	$ (163)	$ 45