Accumulated Other Comprehensive Loss (Components of Accumulated Other Comprehensive Loss) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance at beginning of period			$ 4,394,147
Components of other comprehensive income (loss):
Before reclassifications to income and retained earnings			6,534
Reclassifications to income			14,625
Other comprehensive (loss) income	$ (26,655)	$ 32,346	21,159	$ (83,834)
Balance at end of period	4,113,947	$ 4,514,045	4,113,947	$ 4,514,045
Reclassifications before taxes, included in net periodic benefit expense			2,140
Reclassifications, income tax expense			450
Foreign Currency Translation Gains (Losses)
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance at beginning of period			(324,011)
Components of other comprehensive income (loss):
Before reclassifications to income and retained earnings			6,534
Reclassifications to income			0
Other comprehensive (loss) income			6,534
Balance at end of period	(317,477)		(317,477)
Retirement and Postretirement Benefit Plan Adjustments
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance at beginning of period			(275,632)
Components of other comprehensive income (loss):
Before reclassifications to income and retained earnings			0
Reclassifications to income			12,935
Other comprehensive (loss) income			12,935
Balance at end of period	(262,697)		(262,697)
Reclassifications before taxes, included in net periodic benefit expense			16,282
Deferred Loss on Interest Rate Derivative Hedges
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance at beginning of period			(1,690)
Components of other comprehensive income (loss):
Before reclassifications to income and retained earnings			0
Reclassifications to income			1,690
Other comprehensive (loss) income			1,690
Balance at end of period	0		0
Reclassifications, income tax expense			3,347
Total
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance at beginning of period			(601,333)
Components of other comprehensive income (loss):
Balance at end of period	$ (580,174)		$ (580,174)