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Basis of Presentation and Significant Accounting Policies - Asset Retirement Obligations (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Accounting Policies [Abstract]
Asset Retirement Costs, Estimated Maximum Duration	40 years
Asset Retirement Obligation, Adjustment for Business Acquisition, Foreign Currency Translation Gain (Loss)	$ (4,300)
Asset retirement obligations Abstract
Balance at beginning of period	77,288	$ 90,822	$ 78,036
Costs incurred	(1,608)	(10,380)	(1,011)
Additions/adjustments	(3,284)	(5,030)	8,000
Acquisitions	0	0	2,062
Accretion	5,343	5,379	5,523
Translation	371	(3,503)	(1,788)
Balance at end of period	78,110	77,288	90,822
Current asset retirement obligation	$ 2,800	$ 5,700	$ 13,800

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Asset Retirement Costs, Estimated Maximum Duration

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Asset Retirement Obligation, Business Acquisition

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The carrying amount of a liability for an asset retirement obligation. An asset retirement obligation is a legal obligation associated with the disposal or retirement of a tangible long-lived asset that results from the acquisition, construction or development, or the normal operations of a long-lived asset, except for certain obligations of lessees.

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-Topic 410
-SubTopic 20
-Section 50
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Amount of accretion expense recognized during the period that is associated with an asset retirement obligation. Accretion expense measures and incorporates changes due to the passage of time into the carrying amount of the liability.

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Current portion of the carrying amount of a liability for an asset retirement obligation. An asset retirement obligation is a legal obligation associated with the disposal or retirement of a tangible long-lived asset that results from the acquisition, construction or development, or the normal operations of a long-lived asset, except for certain obligations of lessees.

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Amount of foreign currency translation gain (loss) which decreases (increases) asset retirement obligations.

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Amount of asset retirement obligations settled, or otherwise disposed of, during the period. This may include asset retirement obligations transferred to third parties associated with the sale of a long-lived asset.

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Amount of increase (decrease) in the asset retirement obligation from changes in the amount or timing of the estimated cash flows associated with the settlement of the obligation.

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