For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division.

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Amount, after valuation allowance, recoverable under reinsurance contracts including premium paid under reinsurance contracts. Examples include, but are not limited to, settled and unsettled claims, incurred but not reported losses, loss adjustment expense, premium paid, policy benefits and policy reserves.

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Third-Party Reinsurance - Remaining Gross and Net Reinsurance Recoverables (Details) - Ark Insurance Holdings Limited/Outrigger - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024
Segment Reporting Information [Line Items]
Gross	$ 625.9
Collateral	836.1	$ 589.0
Net	$ 563.6
Reinsurance Recoverable Including Reinsurance Premium Paid \| Reinsurer Concentration Risk
Segment Reporting Information [Line Items]
% of Total	100.00%
Ceded Credit Risk, Secured
Segment Reporting Information [Line Items]
Collateral	$ 62.3
A+ or better
Segment Reporting Information [Line Items]
Gross	404.0
Net	$ 404.0
A+ or better \| Reinsurance Recoverable Including Reinsurance Premium Paid \| Reinsurer Concentration Risk
Segment Reporting Information [Line Items]
% of Total	71.70%
A+ or better \| Ceded Credit Risk, Secured
Segment Reporting Information [Line Items]
Collateral	$ 0.0
A- to A
Segment Reporting Information [Line Items]
Gross	147.7
Net	$ 147.7
A- to A \| Reinsurance Recoverable Including Reinsurance Premium Paid \| Reinsurer Concentration Risk
Segment Reporting Information [Line Items]
% of Total	26.20%
A- to A \| Ceded Credit Risk, Secured
Segment Reporting Information [Line Items]
Collateral	$ 0.0
B++ or lower and not rated
Segment Reporting Information [Line Items]
Gross	74.2
Net	11.9
B++ or lower and not rated \| Ark
Segment Reporting Information [Line Items]
Gross	(34.7)
Collateral	$ (34.7)
B++ or lower and not rated \| Reinsurance Recoverable Including Reinsurance Premium Paid \| Reinsurer Concentration Risk
Segment Reporting Information [Line Items]
% of Total	2.10%
B++ or lower and not rated \| Ceded Credit Risk, Secured
Segment Reporting Information [Line Items]
Collateral	$ 62.3