Investment Securities - Investments In Private Equity Funds Subject to Lock-Up Periods (Details) - USD ($) $ in Millions	Jun. 30, 2024	Dec. 31, 2023
Debt and Equity Securities, FV-NI [Line Items]
1 – 3 years	$ 18.4
3 – 5 years	60.1
5 – 10 years	182.2
>10 years	3.3
Total	2,022.4	$ 1,998.2
Private equity funds
Debt and Equity Securities, FV-NI [Line Items]
Total	$ 264.0