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Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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Income Taxes (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended		12 Months Ended
Income Taxes (Details) - USD ($) $ in Millions	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023	Dec. 31, 2023
Investments, Owned, Federal Income Tax Note [Line Items]
Net deferred tax benefit					$ 68.0
Effective tax rate	(4.80%)	34.60%	6.60%	8.20%
P&C Insurance and Reinsurance (Ark/WM Outrigger) \| Ark
Investments, Owned, Federal Income Tax Note [Line Items]
Net deferred tax benefit					51.0
Financial Guarantee (HG Global) \| HG Global
Investments, Owned, Federal Income Tax Note [Line Items]
Net deferred tax benefit					$ 17.0
Deferred tax liabilities	$ 5.0		$ 5.0
Tax benefit	$ 5.0