Summary of Significant Accounting Policies - Changes in Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	$ 8,126,448	$ 7,440,059	$ 7,067,009
Ending balance	8,541,158	8,126,448	7,440,059
Foreign currency translation adjustments
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	(753,108)	(782,102)	(547,927)
Current period other comprehensive income (loss) before reclassifications	72,853	28,994	(234,175)
Ending balance	(680,255)	(753,108)	(782,102)
Pensions and post-retirement benefits
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	(12,716)	(9,506)	(10,600)
Current period other comprehensive income (loss) before reclassifications	(2,174)	(3,210)	1,094
Ending balance	(14,890)	(12,716)	(9,506)
AOCI including portion attributable to noncontrolling interest
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	(765,824)	(791,608)	(558,527)
Current period other comprehensive income (loss) before reclassifications	70,679	25,784	(233,081)
Ending balance	$ (695,145)	$ (765,824)	$ (791,608)