Investment Securities - Investments In Private Equity Funds Subject to Lock-Up Periods (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Investment securities
1 – 3 years	$ 4.5
3 – 5 years	71.0
5 – 10 years	155.4
>10 years	17.7
Total	1,998.2	$ 1,488.0
Private equity funds
Investment securities
Total	$ 248.6