Accumulated Other Comprehensive Income (Loss) (AOCI balances) (Details 2) - USD ($) $ in Thousands	3 Months Ended				6 Months Ended
	Jun. 30, 2020	Mar. 31, 2020	Jun. 30, 2019	Mar. 31, 2019	Jun. 30, 2020	Jun. 30, 2019
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
As of	$ 3,212,840	$ 3,326,796	$ 2,999,536	$ 2,916,782	$ 3,326,796	$ 2,916,782
Other Comprehensive Income (Loss), Net of Tax	17,068	(37,943)	(12,095)	8,290	(20,875)	(3,805)
As of	3,213,416	3,212,840	3,038,854	$ 2,999,536	3,213,416	3,038,854
AOCI Including Portion Attributable to Noncontrolling Interest [Member]
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
As of		303,295			303,295
Other comprehensive loss before reclassifications					(22,458)
Net amount reclassified from accumulated other comprehensive income (loss)					1,583
Other Comprehensive Income (Loss), Net of Tax					(20,875)
As of	282,420				282,420
Cumulative Foreign Currency Translation Adjustment [Member]
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
As of		(21,888)			(21,888)
Other comprehensive loss before reclassifications					(20,971)
Net amount reclassified from accumulated other comprehensive income (loss)					0
Other Comprehensive Income (Loss), Net of Tax	16,405		(11,104)		(20,971)	(1,071)
As of	(42,859)				(42,859)
Unrealized Gain on Pensions and Other Postretirement Plans [Member]
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
As of		325,921			325,921
Other comprehensive loss before reclassifications					0
Net amount reclassified from accumulated other comprehensive income (loss)	773		(1,026)		1,423	(2,410)
Other Comprehensive Income (Loss), Net of Tax	773		(1,026)		1,423	(2,410)
As of	327,344				327,344
Cash Flow Hedges [Member]
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
As of		$ (738)			(738)
Other comprehensive loss before reclassifications					(1,487)
Net amount reclassified from accumulated other comprehensive income (loss)					160
Other Comprehensive Income (Loss), Net of Tax	(110)		$ 35		(1,327)	$ (324)
As of	$ (2,065)				$ (2,065)