v3.26.3
Investment Securities - Schedule of Estimated Fair Value and Gross Unrealized Losses of Debt Securities in an Unrealized Loss Position (Details) - USD ($)
$ in Millions
Sep. 30, 2026
Dec. 31, 2025
Debt Securities, Available-for-sale [Line Items]    
Fair value, less than one year $ 3,265.1 $ 567.3
Gross unrealized losses, less than one year 160.0 5.0
Fair value, one year or longer 708.0 912.8
Gross unrealized losses, one year or longer 78.0 46.5
Fair Value 3,973.1 1,480.2
Gross Unrealized Losses 238.0 51.5
U.S. treasury notes    
Debt Securities, Available-for-sale [Line Items]    
Fair value, less than one year 71.0 7.4
Gross unrealized losses, less than one year 4.2 0.1
Fair value, one year or longer 254.0 330.8
Gross unrealized losses, one year or longer 19.8 15.8
Fair Value 325.0 338.2
Gross Unrealized Losses 24.0 15.9
Corporate and sovereign debt securities    
Debt Securities, Available-for-sale [Line Items]    
Fair value, less than one year 1,520.5 147.5
Gross unrealized losses, less than one year 78.0 0.7
Fair value, one year or longer 31.9 47.3
Gross unrealized losses, one year or longer 3.6 2.3
Fair Value 1,552.4 194.8
Gross Unrealized Losses 81.6 3.0
Municipal bonds    
Debt Securities, Available-for-sale [Line Items]    
Fair value, less than one year 81.0 50.5
Gross unrealized losses, less than one year 4.5 0.7
Fair value, one year or longer 29.6 34.6
Gross unrealized losses, one year or longer 4.8 3.3
Fair Value 110.6 85.1
Gross Unrealized Losses 9.3 4.0
Asset-backed securities    
Debt Securities, Available-for-sale [Line Items]    
Fair value, less than one year 426.5 134.5
Gross unrealized losses, less than one year 6.3 2.1
Fair value, one year or longer 20.4 22.5
Gross unrealized losses, one year or longer 2.1 0.6
Fair Value 446.8 157.0
Gross Unrealized Losses 8.4 2.7
Mortgage-backed securities    
Debt Securities, Available-for-sale [Line Items]    
Fair value, less than one year 1,166.2 227.4
Gross unrealized losses, less than one year 67.0 1.4
Fair value, one year or longer 372.1 477.7
Gross unrealized losses, one year or longer 47.7 24.5
Fair Value 1,538.3 705.1
Gross Unrealized Losses $ 114.7 $ 25.9