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Income Taxes - Tax Effects of Deferred Tax Assets and Deferred Tax Liabilities (Details) - USD ($) $ in Millions | Dec. 31, 2024 | Dec. 31, 2023
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Income Tax Disclosure [Abstract] |  |
Operating loss carryforwards | $ 181.1 | $ 217.2
Capital loss carryforwards | 17.8 | 9.7
Insurance reserves: Losses and loss adjustment expenses | 111.2 | 104.1
Unrealized losses on investments | 7.4 | 8.9
Accrued expenses | 11.3 | 13.4
Foreign tax credit carryforwards | 22.0 | 19.0
Unearned premiums | 34.5 | 35.0
Intangible assets | 82.7 | 82.9
Office properties and equipment | 14.7 | 16.5
Operating lease liability | 15.0 | 15.6
Other temporary differences | 8.1 | 7.6
Total deferred tax assets | 505.8 | 529.9
Less valuation allowance | (64.0) | (172.7)
Deferred tax assets, net of valuation allowance | 441.8 | 357.2
Deferred acquisition costs | (31.0) | (32.4)
Intangible assets | 0.2 | 0.0
Operating lease assets | (10.4) | (10.4)
Deferred Tax Liabilities, GAAP differences | 0.0 | 0.1
Other temporary differences | (3.4) | (3.3)
Total deferred tax (liabilities) | (45.0) | (46.2)
Deferred tax assets, net | $ 396.8 | $ 311.0

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