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 ($) $ in Millions		3 Months Ended					9 Months Ended	12 Months Ended
	Dec. 20, 2022	Dec. 31, 2024	Sep. 30, 2024	Mar. 31, 2024	Dec. 31, 2023	Dec. 31, 2022	Sep. 30, 2025	Dec. 31, 2024
Outrigger Re
Other Significant Transactions [Line Items]
Ceded unearned premiums		$ 230.0			$ 250.0			$ 230.0
Rollover amount		130.0			$ 130.0
Return of capital			$ 64.9	$ 68.1			$ 5.9	75.0
Total commitment		150.0
Short-term investments, at fair value		$ 203.7					$ 228.4	$ 203.7
Outrigger Re
Other Significant Transactions [Line Items]
Business combination, consideration transferred						$ 205.0
Redeemable Preferred Stock \| Outrigger Re Ltd
Other Significant Transactions [Line Items]
Issuances of common shares	$ 250.0