Fair Value Measurement - Schedule of Financial Assets and Liabilities at Fair Value (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Level 3
Financial liabilities:
Derivative instrument		$ 0
Fair Value, Recurring
Financial assets:
Total financial assets	$ 776,091	833,263
Financial liabilities:
Derivative instrument		0
Total financial liabilities		0
Fair Value, Recurring \| Level 1
Financial assets:
Total financial assets	776,091	833,263
Financial liabilities:
Derivative instrument		0
Total financial liabilities		0
Fair Value, Recurring \| Level 2
Financial assets:
Total financial assets	0	0
Financial liabilities:
Derivative instrument		0
Total financial liabilities		0
Fair Value, Recurring \| Level 3
Financial assets:
Total financial assets	0	0
Financial liabilities:
Derivative instrument		0
Total financial liabilities		0
Fair Value, Recurring \| Money market trust
Financial assets:
Cash and cash equivalents	392,605	629,393
Restricted cash	66,431
Fair Value, Recurring \| Money market trust \| Level 1
Financial assets:
Cash and cash equivalents	392,605	629,393
Restricted cash	66,431
Fair Value, Recurring \| Money market trust \| Level 2
Financial assets:
Cash and cash equivalents	0	0
Restricted cash	0
Fair Value, Recurring \| Money market trust \| Level 3
Financial assets:
Cash and cash equivalents	0	0
Restricted cash	0
Fair Value, Recurring \| Money market fund
Financial assets:
Cash and cash equivalents	35,295	35,641
Long-term restricted cash	2,501
Fair Value, Recurring \| Money market fund \| Level 1
Financial assets:
Cash and cash equivalents	35,295	35,641
Long-term restricted cash	2,501
Fair Value, Recurring \| Money market fund \| Level 2
Financial assets:
Cash and cash equivalents	0	0
Long-term restricted cash	0
Fair Value, Recurring \| Money market fund \| Level 3
Financial assets:
Cash and cash equivalents	0	0
Long-term restricted cash	0
Fair Value, Recurring \| Time deposit
Financial assets:
Restricted cash	270,667	144,949
Other current assets	6,752	18,382
Long-term restricted cash	1,840	4,898
Fair Value, Recurring \| Time deposit \| Level 1
Financial assets:
Restricted cash	270,667	144,949
Other current assets	6,752	18,382
Long-term restricted cash	1,840	4,898
Fair Value, Recurring \| Time deposit \| Level 2
Financial assets:
Restricted cash	0	0
Other current assets	0	0
Long-term restricted cash	0	0
Fair Value, Recurring \| Time deposit \| Level 3
Financial assets:
Restricted cash	0	0
Other current assets	0	0
Long-term restricted cash	$ 0	$ 0

Fair value portion of probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)
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Fair value portion of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes 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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Fair value, after the effects of master netting arrangements, of a financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes liabilities not subject to a master netting arrangement and not elected to be offset.

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
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Fair value of financial obligations, including, but not limited to, debt instruments, derivative liabilities, federal funds purchased and sold under agreements to repurchase, securities loaned or sold under agreements to repurchase, financial instruments sold not yet purchased, guarantees, line of credit, loans and notes payable, servicing liability, and trading liabilities.

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- Definition

Fair value portion of other assets.

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- Definition

Amount of cash 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.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
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Amount of cash 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.

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Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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