v3.26.3
Investment Securities - Fair Value of Hedge Funds Subject to Restrictions on Redemption Frequency (Details) - USD ($)
$ in Millions
Sep. 30, 2026
Dec. 31, 2025
Total private equity funds and hedge funds    
Debt and Equity Securities, FV-NI [Line Items]    
Fair Value $ 487.7 $ 395.2
Unfunded Commitments 81.1 65.8
Private equity funds    
Debt and Equity Securities, FV-NI [Line Items]    
Fair Value 257.1 251.2
Unfunded Commitments 81.1 65.8
Private equity funds | Aerospace/Defense/Government    
Debt and Equity Securities, FV-NI [Line Items]    
Fair Value 146.8 144.0
Unfunded Commitments 30.5 39.9
Private equity funds | Financial services    
Debt and Equity Securities, FV-NI [Line Items]    
Fair Value 107.6 104.2
Unfunded Commitments 48.4 23.7
Private equity funds | Real estate    
Debt and Equity Securities, FV-NI [Line Items]    
Fair Value 2.7 3.0
Unfunded Commitments 2.2 2.2
Hedge funds    
Debt and Equity Securities, FV-NI [Line Items]    
Fair Value 230.6 144.0
Unfunded Commitments 0.0 0.0
Hedge funds | Long/short all cap global    
Debt and Equity Securities, FV-NI [Line Items]    
Fair Value 166.8 110.6
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 63.8 33.4
Unfunded Commitments $ 0.0 $ 0.0