Accumulated Other Comprehensive Loss (Reclassification) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Reclassification out of Accumulated Other Comprehensive Income [Line Items]
Other income (expense), net	$ (994)	$ 5,019	$ 1,167
Income tax expense	(22,938)	(52,466)	(33,997)
Net income	87,651	80,459	$ 48,283
Amounts reclassified from accumulated other comprehensive income (loss) for the period ended December 31, 2013 | Funded status of pension plans and other postretirement benefits
Reclassification out of Accumulated Other Comprehensive Income [Line Items]
Other income (expense), net	(227)	(154)
Income tax expense	51	55
Net income	(176)	(99)
Amounts reclassified from accumulated other comprehensive income (loss) for the period ended December 31, 2013 | Unrealized gain (loss) on derivative instruments
Reclassification out of Accumulated Other Comprehensive Income [Line Items]
Other income (expense), net	247	(51)
Income tax expense	(56)	19
Net income	$ 191	$ (32)