Debt Commitments - Senior Unsecured Promissory Notes Payable (Details) - Senior Unsecured Promissory Notes	Sep. 30, 2021 USD ($)
Debt Instrument [Line Items]
Debt issuance, aggregate principal amount	$ 365,000,000.0
Maximum aggregate borrowing capacity	$ 600,000,000.0

Face (par) amount of debt instrument at time of issuance.

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Name:	us-gaap_DebtInstrumentFaceAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant