Investment Securities - Fair Value of Hedge Funds and Private Equity Funds (Details) - USD ($) $ in Millions	Mar. 31, 2023	Dec. 31, 2022
Total private equity funds and hedge funds included in other long-term investments
Debt and Equity Securities, FV-NI [Line Items]
Fair Value	$ 218.5	$ 197.8
Unfunded Commitments	92.6	94.3
Private equity funds
Debt and Equity Securities, FV-NI [Line Items]
Fair Value	159.4	140.6
Unfunded Commitments	92.6	94.3
Private equity funds | Aerospace/Defense/Government
Debt and Equity Securities, FV-NI [Line Items]
Fair Value	78.0	59.4
Unfunded Commitments	37.5	37.5
Private equity funds | Financial services
Debt and Equity Securities, FV-NI [Line Items]
Fair Value	77.3	77.1
Unfunded Commitments	52.6	54.3
Private equity funds | Real estate
Debt and Equity Securities, FV-NI [Line Items]
Fair Value	4.1	4.1
Unfunded Commitments	2.5	2.5
Hedge funds
Debt and Equity Securities, FV-NI [Line Items]
Fair Value	59.1	57.2
Unfunded Commitments	0.0	0.0
Hedge funds | Long/short equity financials and business services
Debt and Equity Securities, FV-NI [Line Items]
Fair Value	49.8	49.0
Unfunded Commitments	0.0	0.0
Hedge funds | European small/mid cap
Debt and Equity Securities, FV-NI [Line Items]
Fair Value	9.3	8.2
Unfunded Commitments	$ 0.0	$ 0.0