Accumulated Other Comprehensive Income (Loss) (AOCI balances) (Details 2) - USD ($) $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Sep. 30, 2021	Sep. 30, 2020
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
As of	$ 3,975,912	$ 3,864,839	$ 3,766,393	$ 3,213,416	$ 3,212,840	$ 3,326,796	$ 3,766,393	$ 3,326,796
Other Comprehensive (Loss) Income, Net of Tax	(16,126)	1,080	(1,203)	21,263	17,068	(37,943)	(16,249)	388
As of	3,973,738	$ 3,975,912	3,864,839	3,246,658	$ 3,213,416	$ 3,212,840	3,973,738	3,246,658
AOCI Including Portion Attributable to Noncontrolling Interest [Member]
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
As of			603,314				603,314
Other comprehensive (loss) income before reclassifications							(15,191)
Net amount reclassified from accumulated other comprehensive income (loss)							(1,058)
Other Comprehensive (Loss) Income, Net of Tax							(16,249)
As of	587,065						587,065
Cumulative Foreign Currency Translation Adjustment [Member]
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
As of			9,754				9,754
Other comprehensive (loss) income before reclassifications							(15,352)
Net amount reclassified from accumulated other comprehensive income (loss)							0
Other Comprehensive (Loss) Income, Net of Tax	(16,033)			20,430			(15,352)	(541)
As of	(5,598)						(5,598)
Unrealized Gain on Pensions and Other Postretirement Plans [Member]
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
As of			595,287				595,287
Other comprehensive (loss) income before reclassifications							0
Net amount reclassified from accumulated other comprehensive income (loss)	(223)			712			(1,514)	2,135
Other Comprehensive (Loss) Income, Net of Tax	(223)			712			(1,514)	2,135
As of	593,773						593,773
Cash Flow Hedges [Member]
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
As of			$ (1,727)				(1,727)
Other comprehensive (loss) income before reclassifications							161
Net amount reclassified from accumulated other comprehensive income (loss)							456
Other Comprehensive (Loss) Income, Net of Tax	130			$ 121			617	$ (1,206)
As of	$ (1,110)						$ (1,110)