Supplemental Cash Flow Information (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Feb. 02, 2021	Dec. 31, 2020	Sep. 30, 2020	Dec. 31, 2019
Supplemental Cash Flow Information [Abstract]
Cash and cash equivalents	$ 258,024	$ 172,768	$ 188,006	$ 207,781	$ 272,624
Restricted cash-current		16,751
Restricted cash-current	79,560	80,179	80,178	80,175	2,764
Cash, cash equivalents, and restricted cash	$ 337,584	$ 269,698	$ 268,184	$ 287,956	$ 275,388

Amount of cash and cash equivalents restricted as to withdrawal or usage, classified as noncurrent. Cash includes, but is not limited to, currency on hand, demand deposits with banks or financial institutions, and other accounts with general characteristics of demand deposits. Cash equivalents include, but are not limited to, short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates.

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant