Reinsurance - Schedule of Reinsurance Recoverable (Details) - USD ($) $ in Millions |
6 Months Ended | |||
|---|---|---|---|---|
Jun. 30, 2026 |
Dec. 31, 2025 |
Jun. 30, 2025 |
Dec. 31, 2024 |
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| Insurance [Abstract] | ||||
| Reinsurance recoverables on unpaid losses and LAE | $ 2,092.9 | $ 1,682.3 | $ 1,424.6 | $ 1,069.5 |
| Other reinsurance recoverables: | ||||
| Reinsurance recoverables on paid losses and LAE | 763.7 | 512.7 | ||
| Deposit assets | 61.4 | 69.5 | ||
| Commutation consideration receivable | 116.7 | 12.0 | ||
| Total other reinsurance recoverables | 941.8 | 594.2 | ||
| Reinsurance recoverables | 3,034.7 | $ 2,276.5 | ||
| Loss portfolio transfer, reduction in deposit assets, attributable to actual recoveries | 8.1 | |||
| Decrease related to recoveries | (8.4) | |||
| Increase related to income amortization | $ 0.3 |
| X | ||||||||||
- Definition Increase (Decrease) In Reinsurance, Loss Portfolio Transfer, Deposit Assets No definition available.
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| X | ||||||||||
- Definition Increase (Decrease) In Reinsurance Recoverable, Deposit Assets, Income Amortization No definition available.
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- Definition Increase (Decrease) In Reinsurance Recoverable, Deposit Assets, Recoveries No definition available.
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| X | ||||||||||
- Definition Other Reinsurance Recoverables No definition available.
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| X | ||||||||||
- Definition Reinsurance Recoverable, Commutation Consideration Receivable No definition available.
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- Definition Reinsurance Recoverable, Deposit Assets No definition available.
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| X | ||||||||||
- Definition Reinsurance Recoverable For Paid Claims And Claim Adjustments, Including Deposit Assets No definition available.
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| X | ||||||||||
- References No definition available.
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- Definition Amount, after valuation allowance, recoverable under reinsurance contracts for losses reported to the ceding insurer but not yet paid and amounts expected for incurred losses and settlement expenses, which have not yet been reported to the ceding insurer. Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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| X | ||||||||||
- Definition 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. Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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| X | ||||||||||
- Definition Amount, after valuation allowance, recoverable under reinsurance contracts for losses reported to and paid by the ceding insurer. Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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