Investments - Investment in related party investment funds (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Debt and Equity Securities, FV-NI [Line Items]
Investments in related party investment funds, Cost	$ 441.9	$ 891.9
Investment in related party investment funds, Fair value	909.6	1,055.6
Third Point Enhanced LP
Debt and Equity Securities, FV-NI [Line Items]
Investments in related party investment funds, Cost	416.0	891.9
Investment in related party investment funds, Fair value	878.2	1,055.6
Third Point Venture Offshore Fund I LP
Debt and Equity Securities, FV-NI [Line Items]
Investments in related party investment funds, Cost	25.9	0.0
Investment in related party investment funds, Fair value	$ 31.4	$ 0.0