Other Comprehensive Income (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018	Dec. 31, 2016
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated Other Comprehensive Income (Loss), Net of Tax	$ (301,433)	$ (265,721)	$ (302,414)	$ (265,406)
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	(2,957)	1,782
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax	(1,799)	(10,029)
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	5,737	7,932
Other Comprehensive Income (Loss), Net of Tax	981	(315)
Accumulated Translation Adjustment [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated Other Comprehensive Income (Loss), Net of Tax	(64,598)	(45,234)	(63,913)	(31,340)
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	0	0
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax	(685)	(13,894)
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	0	0
Other Comprehensive Income (Loss), Net of Tax	(685)	(13,894)
Accumulated Gain (Loss), Net, Cash Flow Hedge, Parent [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated Other Comprehensive Income (Loss), Net of Tax	(2,523)	1,383	702	(1,081)
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	(2,957)	1,782
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax	0	0
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	(268)	682
Other Comprehensive Income (Loss), Net of Tax	(3,225)	2,464
Accumulated Defined Benefit Plans Adjustment [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated Other Comprehensive Income (Loss), Net of Tax	(234,312)	(221,870)	$ (239,203)	$ (232,985)
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	0	0
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax	(1,114)	3,865
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	6,005	7,250
Other Comprehensive Income (Loss), Net of Tax	$ 4,891	$ 11,115