Asset Retirement Obligations - Schedule of Reconciliation of Beginning and Ending Aggregate Carrying Amount of Asset Retirement Obligations (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Balance at beginning of year	$ 865,109	$ 800,117
Accretion expense	42,136	40,506	$ 27,119	[1]
Liabilities incurred	14,736	14,759
Liabilities assumed from acquisitions	0	64,810
Revisions of previous estimates	(70,098)	(34,371)
Liabilities settled	(4,816)	(25,544)
Liabilities associated with assets held for sale	(21)	(240)
Changes due to translation of foreign currencies	2,910	5,072
Balance at end of year	$ 849,956	$ 865,109	$ 800,117

[1] Reclassified to conform with current presentation