Investment Securities - Fair Value of Hedge Funds and Private Equity Funds (Details) - USD ($) $ in Millions	Jun. 30, 2022	Dec. 31, 2021
Hedge and private equity funds included in other long-term investments
Debt and Equity Securities, FV-NI [Line Items]
Fair Value	$ 200.1	$ 153.8
Unfunded Commitments	101.6	44.0
Private equity funds
Debt and Equity Securities, FV-NI [Line Items]
Fair Value	191.7	141.8
Unfunded Commitments	101.6	44.0
Private equity funds | Aerospace/Defense/Government
Debt and Equity Securities, FV-NI [Line Items]
Fair Value	107.0	69.8
Unfunded Commitments	43.5	11.8
Private equity funds | Financial services
Debt and Equity Securities, FV-NI [Line Items]
Fair Value	80.0	67.7
Unfunded Commitments	55.6	29.3
Private equity funds | Real estate
Debt and Equity Securities, FV-NI [Line Items]
Fair Value	4.7	4.3
Unfunded Commitments	2.5	2.9
Hedge funds
Debt and Equity Securities, FV-NI [Line Items]
Fair Value	8.4	12.0
Unfunded Commitments	0.0	0.0
Hedge funds | European small/mid cap
Debt and Equity Securities, FV-NI [Line Items]
Fair Value	8.4	12.0
Unfunded Commitments	$ 0.0	$ 0.0