Accumulated Other Comprehensive Income (Loss) (AOCI balances) (Details 2) - USD ($) $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Sep. 30, 2019	Sep. 30, 2018
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
As of	$ 3,038,854	$ 2,999,536	$ 2,916,782	$ 2,876,864	$ 2,884,388	$ 2,915,145	$ 2,916,782	$ 2,915,145
Other Comprehensive Loss, Net of Tax	(18,086)	(12,095)	8,290	(5,202)	(33,221)	10,812	(21,891)	(27,611)
As of	3,058,911	$ 3,038,854	2,999,536	2,974,831	$ 2,876,864	$ 2,884,388	3,058,911	2,974,831
AOCI Including Portion Attributable to Noncontrolling Interest [Member]
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
As of			203,829				203,829
Other comprehensive loss before reclassifications							(18,317)
Net amount reclassified from accumulated other comprehensive income (loss)							(3,574)
Other Comprehensive Loss, Net of Tax							(21,891)
As of	181,938						181,938
Cumulative Foreign Currency Translation Adjustment [Member]
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
As of			(29,270)				(29,270)
Other comprehensive loss before reclassifications							(17,755)
Net amount reclassified from accumulated other comprehensive income (loss)							0
Other Comprehensive Loss, Net of Tax	(16,684)			(2,844)			(17,755)	(22,447)
As of	(47,025)						(47,025)
Unrealized Gain on Pensions and Other Postretirement Plans [Member]
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
As of			232,836				232,836
Other comprehensive loss before reclassifications							0
Net amount reclassified from accumulated other comprehensive income (loss)	(1,053)			(2,353)			(3,463)	(5,651)
Other Comprehensive Loss, Net of Tax	(1,053)			(2,353)			(3,463)	(5,651)
As of	229,373						229,373
Cash Flow Hedges [Member]
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
As of			$ 263				263
Other comprehensive loss before reclassifications							(562)
Net amount reclassified from accumulated other comprehensive income (loss)							(111)
Other Comprehensive Loss, Net of Tax	(349)			$ (5)			(673)	$ 487
As of	$ (410)						$ (410)