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Reinsurance (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
Fronting
SEC Schedule, 12-17, Insurance Companies, Reinsurance [Line Items]
Gross losses and loss adjustment expenses	$ 1,200.0	$ 975.0	$ 3,400.0	$ 2,200.0

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Amount, before effect of policies assumed or ceded, of expense related to provision for policy benefits and costs incurred.

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