Equity impact of the value of new stock issued during the period. Includes shares issued in an initial public offering or a secondary public offering.

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Significant Transactions - Outrigger Re (Details) - USD ($)		3 Months Ended
	Dec. 20, 2022	Mar. 31, 2025	Dec. 31, 2024	Mar. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Redeemable Preferred Stock \| Outrigger Re Ltd
Other Significant Transactions [Line Items]
Issuances of common shares	$ 250,000,000
Outrigger Re
Other Significant Transactions [Line Items]
Business Combination, Consideration Transferred						$ 205,000,000
Outrigger Re
Other Significant Transactions [Line Items]
Ceded unearned premiums			$ 230,000,000		$ 250,000,000
Rollover amount			130,000,000		130,000,000
Return of capital		$ 0		$ 68,100,000	$ 75,000,000
Prepaid Reinsurance Premium, Commitment Amount			150,000,000
Short-term investments, at fair value		$ 208,700,000	$ 203,700,000