Third-Party Reinsurance - Reinsurance Recoverables (Details) - USD ($) $ in Millions	Mar. 31, 2023	Dec. 31, 2022
Ark
Reinsurance [Line Items]
Reinsurance recoverables on unpaid losses	$ 348.9	$ 505.0
Reinsurance recoverables on paid losses	23.1	31.1
Ceded unearned premiums	198.6	59.2
Reinsurance recoverables	$ 570.6	595.3
Ark \| Third Point Re
Reinsurance [Line Items]
Annual crediting rate	3.00%
Carrying value of investment	$ 20.6
P&C Insurance and Reinsurance (Ark/WM Outrigger)
Reinsurance [Line Items]
Reinsurance recoverables on unpaid losses	0.2
Ceded unearned premiums	$ (38.9)
TPC Providers
Reinsurance [Line Items]
Reinsurance recoverables on unpaid losses		$ 145.4

Value of the investment at close of period. For schedules of investments that are categorized, the value would be aggregated by category. For investment in and advances to affiliates, if operations of any controlled companies are different in character from those of the company, group such affiliates within divisions and by type of activities.

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Rate of interest credited to policyholder deposits.

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Amount before valuation allowance recoverable 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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Amount before valuation allowance of reinsurance recoverables on paid losses.

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Amount before valuation allowance of reinsurance recoverables for losses reported to the ceding insurer but not yet paid, and for amounts expected based upon statistical projections and other measures of incurred losses and loss settlement expenses which have not yet been reported to the ceding insurer.

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Reinsurance [Line Items]

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Reinsurance Recoverables on Unpaid Losses, Ceded Unearned Premiums

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