Accumulated Other Comprehensive Loss (Reclassifications out of AOCI) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net of tax	$ (1,464)	$ (1,828)	$ (4,475)	$ (5,570)
Amortization of actuarial losses
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Reclassification	(1,564)	(2,061)	(4,727)	(6,231)
Prior service costs
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Reclassification	(131)	(78)	(408)	(237)
Pension and other post-retirement effects
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Tax benefit	231	311	660	898
Net of tax	$ (1,464)	$ (1,828)	$ (4,475)	$ (5,570)