Amount of cash and cash equivalents restricted as to withdrawal or usage, classified as current. 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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Name:	us-gaap_RestrictedCashAndCashEquivalentsAtCarryingValue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

Cash, Cash Equivalents and Restricted Cash (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020	Jun. 30, 2020	Dec. 31, 2019
Cash and Cash Equivalents [Line Items]
Cash and cash equivalents	$ 231,129	$ 374,289
Restricted cash	2,884	77,563
Total cash, cash equivalents and restricted cash	234,013	451,852	$ 191,491	$ 202,101
Restricted cash held to repay outstanding principal balance of Convertible Notes		69,900
Joint venture cash and cash equivalents
Cash and Cash Equivalents [Line Items]
Cash and cash equivalents	127,606	163,448
Cash and cash equivalents available for general corporate purposes
Cash and Cash Equivalents [Line Items]
Cash and cash equivalents	$ 103,523	$ 210,841