Restricted Cash and Investments - Narrative (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021	Oct. 01, 2021	Sep. 30, 2021
Restricted Investments Note [Abstract]
Guaranteed interest rate on deposit (as a percent)			0.09%	4.00%
Restricted investments	$ 196,820	$ 320,052
Restricted cash and short-term investments	$ 196,820	$ 246,350

Rate of interest on investment.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=123581744&loc=d3e27232-111563

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=123581744&loc=d3e27161-111563

+ Details

Name:	us-gaap_InvestmentInterestRate
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Investments which are not defined as or included in marketable (debt, equity, or other) securities whose use is restricted in whole or in part, generally by contractual agreements or regulatory requirements. For use in an unclassified balance sheet.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 954
-SubTopic 210
-Section 45
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=120413173&loc=SL6242262-115580

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 954
-SubTopic 210
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=120413209&loc=SL6242269-115581

+ Details

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

- Definition

This element represents the current portion of investments which are not defined as or included in marketable (debt, equity, or other) securities that are pledged or subject to withdrawal restrictions.

+ References

+ Details

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

- References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration