Income Taxes (Details) - USD ($) $ in Millions	Mar. 31, 2023	Dec. 31, 2022
US Treasury Securities
Operating Loss Carryforwards [Line Items]
Debt securities	$ 596.4	$ 596.4
Internal Revenue Service (IRS)
Operating Loss Carryforwards [Line Items]
Current federal income tax liability	$ 21.4	$ 21.4

Carrying value as of the balance sheet date of obligations incurred and payable for statutory income, sales, use, payroll, excise, real, property and other taxes.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(20))
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Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
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-Subparagraph (SX 210.9-03(15)(1))
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Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant