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Equity Method Investments (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
Equity Method Investments (Details) - USD ($) $ in Millions	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023	Sep. 12, 2024	Dec. 31, 2023
Schedule of Equity Method Investments [Line Items]
Equity method investments	$ 849.9		$ 849.9			$ 605.9
Income (loss) from equity method investments	9.8	$ 4.2	45.4	$ (0.4)
Hagerty, Inc. [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investments	$ 260.8		$ 260.8			$ 237.4
Equity method investment, ownership percentage	23.00%		23.00%			23.00%
Equity method investment, quoted market value	$ 793.3		$ 793.3			$ 608.4
Sponsor organization of the US Exchange Visitor Program
Schedule of Equity Method Investments [Line Items]
Equity method investments					$ 167.7
Equity method investment, ownership percentage					68.00%