| Investments - Schedule of Unamortized Capitalized Fee Income (Details) - USD ($) $ in Millions | 3 Months Ended | 12 Months Ended | 
|---|---|---|
| Mar. 31, 2024 | Dec. 31, 2023 | |
| Accounts, Notes, Loans and Financing Receivable [Line Items] | ||
| Total Unamortized Fee Income | $ 47.6 | $ 42.3 | 
| Included in Cost | ||
| Accounts, Notes, Loans and Financing Receivable [Line Items] | ||
| Total Unamortized Fee Income | 37.0 | 32.9 | 
| Deferred Fees | ||
| Accounts, Notes, Loans and Financing Receivable [Line Items] | ||
| Total Unamortized Fee Income | $ 10.6 | $ 9.4 | 
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- Definition Unamortized Fee Income No definition available. 
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- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. No definition available. 
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