Accumulated Other Comprehensive Loss (Components of Accumulated Other Comprehensive Loss) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 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			37,842
Reclassifications to income			9,972
Other comprehensive (loss) income	$ 22,091	$ 11,643	47,814	$ (116,180)
Balance at end of period	4,041,828	$ 4,773,482	4,041,828	$ 4,773,482
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			37,842
Reclassifications to income			0
Other comprehensive (loss) income			37,842
Balance at end of period	(286,169)		(286,169)
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			8,282
Other comprehensive (loss) income			8,282
Balance at end of period	(267,350)		(267,350)
Reclassifications before taxes, included in net periodic benefit expense			10,513
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			2,231
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	$ (553,519)		$ (553,519)