Equity-Method Eligible Investments - Carrying Values of Equity Method Eligible Investments Recorded within Other Long-Term Investments (Details) - USD ($) $ in Millions	Sep. 30, 2022	Dec. 31, 2021	May 07, 2020	May 06, 2020
Investments in unconsolidated affiliates
Other long-term investments	$ 1,622.7	$ 1,377.8
Kudu investments
Investments in unconsolidated affiliates
Other long-term investments	$ 813.2	$ 669.5
Kudu investments | Minimum
Investments in unconsolidated affiliates
Ownership interest (as a percent)	4.10%	3.20%
Kudu investments | Maximum
Investments in unconsolidated affiliates
Ownership interest (as a percent)	33.00%	32.00%
Marketing Technology (MediaAlpha)
Investments in unconsolidated affiliates
Ownership interest (as a percent)	27.40%	28.00%
Other long-term investments	$ 148.2	$ 261.6
PassportCard/DavidShield
Investments in unconsolidated affiliates
Ownership interest (as a percent)	53.80%	53.80%	53.80%	50.00%
Other long-term investments	$ 132.0	$ 120.0
Elementum Holdings, L.P.
Investments in unconsolidated affiliates
Ownership interest (as a percent)	29.70%	29.70%
Other long-term investments	$ 45.0	$ 45.0
Other
Investments in unconsolidated affiliates
Other long-term investments	102.7	109.3
Equity Method Investments
Investments in unconsolidated affiliates
Other long-term investments	$ 27.7	$ 17.8