Accumulated Other Comprehensive Loss (Components of Accumulated Other Comprehensive Loss) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance at beginning of period			$ 5,804,611
Components of other comprehensive income (loss):
Before reclassifications to income and retained earnings			(95,227)
Reclassifications to income			11,393
Other comprehensive (loss) income	$ 32,346	$ (13,782)	(83,834)	$ 46,960
Balance at end of period	4,514,045	$ 6,025,820	4,514,045	$ 6,025,820
Reclassifications before taxes, included in net periodic benefit expense			1,147
Reclassifications, income tax expense			242
Foreign Currency Translation Gains (Losses)
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance at beginning of period			(353,252)
Components of other comprehensive income (loss):
Before reclassifications to income and retained earnings			(39,520)
Reclassifications to income			0
Other comprehensive (loss) income			(39,520)
Balance at end of period	(392,772)		(392,772)
Retirement and Postretirement Benefit Plan Adjustments
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance at beginning of period			(218,015)
Components of other comprehensive income (loss):
Before reclassifications to income and retained earnings			(55,707)
Reclassifications to income			10,488
Other comprehensive (loss) income			(45,219)
Balance at end of period	(263,234)		(263,234)
Reclassifications before taxes, included in net periodic benefit expense			13,720
Deferred Loss on Interest Rate Derivative Hedges
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance at beginning of period			(2,894)
Components of other comprehensive income (loss):
Before reclassifications to income and retained earnings			0
Reclassifications to income			905
Other comprehensive (loss) income			905
Balance at end of period	(1,989)		(1,989)
Reclassifications, income tax expense			3,232
Total
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance at beginning of period			(574,161)
Components of other comprehensive income (loss):
Balance at end of period	$ (657,995)		$ (657,995)