Equity Method Eligible Investments - Ownership Interests and Carrying Values (Details) - USD ($) $ in Millions	Sep. 30, 2024	Dec. 31, 2023
Kudu's Participation Contracts
Investments in unconsolidated affiliates
Carrying Value	$ 930.6	$ 890.5
Kudu's Participation Contracts | Minimum
Investments in unconsolidated affiliates
Ownership Interest	4.10%	4.10%
Kudu's Participation Contracts | Maximum
Investments in unconsolidated affiliates
Ownership Interest	30.00%	30.00%
MediaAlpha
Investments in unconsolidated affiliates
Ownership Interest	26.80%	34.90%
Carrying Value	$ 323.4	$ 254.9
PassportCard/DavidShield
Investments in unconsolidated affiliates
Ownership Interest	53.80%	53.80%
Carrying Value	$ 150.0	$ 150.0
Elementum
Investments in unconsolidated affiliates
Ownership Interest	26.60%	26.60%
Carrying Value	$ 35.0	$ 35.0
Other equity method eligible investments, at fair value
Investments in unconsolidated affiliates
Carrying Value	243.9	291.7
Other equity method eligible investments, at fair value
Investments in unconsolidated affiliates
Carrying Value	$ 0.0	$ 24.8