v3.25.2
Fair Value Measurements (Recurring Basis Hierarchy Leveling) (Details) - USD ($)
$ in Millions
Jun. 30, 2025
Dec. 31, 2024
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Available for Sale $ 32,250.4 $ 29,001.5
Derivative Assets 4,066.5 5,358.5
NETTING (3,175.5) (1,910.4)
Derivative Assets 891.0 3,448.1
Derivative Liabilities 4,537.7 5,158.4
NETTING (2,380.7) (4,199.6)
Derivative Liabilities 2,157.0 958.8
Cross Product Collateral Adjustment    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
NETTING (1,600.0) (368.2)
NETTING (820.0) (2,700.0)
U.S. Government    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Available for Sale 8,286.0 7,367.5
Obligations of States and Political Subdivisions    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Available for Sale 306.8 297.6
Government Sponsored Agency    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Available for Sale 15,838.9 13,288.9
Non-U.S. Government    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Available for Sale 313.2 296.8
Corporate Debt    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Available for Sale 93.4 163.8
Covered Bonds    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Available for Sale 235.5 230.9
Sub-Sovereign, Supranational and Non-U.S. Agency Bonds    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Available for Sale 4,970.9 4,583.1
Other Asset-Backed    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Available for Sale 1,687.9 2,182.7
Commercial Mortgage-Backed    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Available for Sale 517.8 590.2
LEVEL 2    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Available for Sale 24,000.0 21,600.0
Fair Value, Measurements, Recurring    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Available for Sale 32,250.4 29,001.5
Fair Value, Measurements, Recurring | U.S. Government    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Available for Sale 8,286.0 7,367.5
Fair Value, Measurements, Recurring | Obligations of States and Political Subdivisions    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Available for Sale 306.8 297.6
Fair Value, Measurements, Recurring | Government Sponsored Agency    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Available for Sale 15,838.9 13,288.9
Fair Value, Measurements, Recurring | Non-U.S. Government    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Available for Sale 313.2 296.8
Fair Value, Measurements, Recurring | Corporate Debt    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Available for Sale 93.4 163.8
Fair Value, Measurements, Recurring | Covered Bonds    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Available for Sale 235.5 230.9
Fair Value, Measurements, Recurring | Sub-Sovereign, Supranational and Non-U.S. Agency Bonds    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Available for Sale 4,970.9 4,583.1
Fair Value, Measurements, Recurring | Other Asset-Backed    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Available for Sale 1,687.9 2,182.7
Fair Value, Measurements, Recurring | Commercial Mortgage-Backed    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Available for Sale 517.8 590.2
Fair Value, Measurements, Recurring | Other Assets    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Equity Securities 106.7 111.3
NETTING (3,175.5) (1,910.4)
Derivative Assets 891.0 3,448.1
Fair Value, Measurements, Recurring | Other Assets | Money market investment    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Equity Securities 85.0  
Fair Value, Measurements, Recurring | Other Assets | Visa Class C shares    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Equity Securities 21.7  
Fair Value, Measurements, Recurring | Other Assets | Foreign Exchange Contracts    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
NETTING (3,074.7) (1,745.2)
Derivative Assets 622.4 3,252.1
Fair Value, Measurements, Recurring | Other Assets | Interest Rate Contracts    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
NETTING (100.8) (165.2)
Derivative Assets 268.6 196.0
Fair Value, Measurements, Recurring | Other Liabilities    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
NETTING (2,380.7) (4,199.6)
Derivative Liabilities 2,157.0 958.8
Fair Value, Measurements, Recurring | Other Liabilities | Foreign Exchange Contracts    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
NETTING (2,353.8) (4,197.3)
Derivative Liabilities 1,758.5 512.5
Fair Value, Measurements, Recurring | Other Liabilities | Interest Rate Contracts    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
NETTING (5.4) (2.3)
Derivative Liabilities 397.2 419.1
Fair Value, Measurements, Recurring | Other Liabilities | Other Financial Derivatives    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
NETTING (21.5) 0.0
Derivative Liabilities 1.3 27.2
Fair Value, Measurements, Recurring | LEVEL 1    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Available for Sale 8,286.0 7,367.5
Fair Value, Measurements, Recurring | LEVEL 1 | U.S. Government    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Available for Sale 8,286.0 7,367.5
Fair Value, Measurements, Recurring | LEVEL 1 | Obligations of States and Political Subdivisions    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Available for Sale 0.0 0.0
Fair Value, Measurements, Recurring | LEVEL 1 | Government Sponsored Agency    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Available for Sale 0.0 0.0
Fair Value, Measurements, Recurring | LEVEL 1 | Non-U.S. Government    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Available for Sale 0.0 0.0
Fair Value, Measurements, Recurring | LEVEL 1 | Corporate Debt    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Available for Sale 0.0 0.0
Fair Value, Measurements, Recurring | LEVEL 1 | Covered Bonds    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Available for Sale 0.0 0.0
Fair Value, Measurements, Recurring | LEVEL 1 | Sub-Sovereign, Supranational and Non-U.S. Agency Bonds    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Available for Sale 0.0 0.0
Fair Value, Measurements, Recurring | LEVEL 1 | Other Asset-Backed    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Available for Sale 0.0 0.0
Fair Value, Measurements, Recurring | LEVEL 1 | Commercial Mortgage-Backed    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Available for Sale 0.0 0.0
Fair Value, Measurements, Recurring | LEVEL 1 | Other Assets    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Equity Securities 85.0 85.0
Derivative Assets 0.0 0.0
Fair Value, Measurements, Recurring | LEVEL 1 | Other Assets | Foreign Exchange Contracts    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Derivative Assets 0.0 0.0
Fair Value, Measurements, Recurring | LEVEL 1 | Other Assets | Interest Rate Contracts    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Derivative Assets 0.0 0.0
Fair Value, Measurements, Recurring | LEVEL 1 | Other Liabilities    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Derivative Liabilities 0.0 0.0
Fair Value, Measurements, Recurring | LEVEL 1 | Other Liabilities | Foreign Exchange Contracts    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Derivative Liabilities 0.0 0.0
Fair Value, Measurements, Recurring | LEVEL 1 | Other Liabilities | Interest Rate Contracts    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Derivative Liabilities 0.0 0.0
Fair Value, Measurements, Recurring | LEVEL 1 | Other Liabilities | Other Financial Derivatives    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Derivative Liabilities 0.0 0.0
Fair Value, Measurements, Recurring | LEVEL 2    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Available for Sale 23,964.4 21,634.0
Fair Value, Measurements, Recurring | LEVEL 2 | U.S. Government    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Available for Sale 0.0 0.0
Fair Value, Measurements, Recurring | LEVEL 2 | Obligations of States and Political Subdivisions    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Available for Sale 306.8 297.6
Fair Value, Measurements, Recurring | LEVEL 2 | Government Sponsored Agency    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Available for Sale 15,838.9 13,288.9
Fair Value, Measurements, Recurring | LEVEL 2 | Non-U.S. Government    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Available for Sale 313.2 296.8
Fair Value, Measurements, Recurring | LEVEL 2 | Corporate Debt    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Available for Sale 93.4 163.8
Fair Value, Measurements, Recurring | LEVEL 2 | Covered Bonds    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Available for Sale 235.5 230.9
Fair Value, Measurements, Recurring | LEVEL 2 | Sub-Sovereign, Supranational and Non-U.S. Agency Bonds    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Available for Sale 4,970.9 4,583.1
Fair Value, Measurements, Recurring | LEVEL 2 | Other Asset-Backed    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Available for Sale 1,687.9 2,182.7
Fair Value, Measurements, Recurring | LEVEL 2 | Commercial Mortgage-Backed    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Available for Sale 517.8 590.2
Fair Value, Measurements, Recurring | LEVEL 2 | Other Assets    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Equity Securities 21.7 26.3
Derivative Assets 4,066.5 5,358.5
Fair Value, Measurements, Recurring | LEVEL 2 | Other Assets | Foreign Exchange Contracts    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Derivative Assets 3,697.1 4,997.3
Fair Value, Measurements, Recurring | LEVEL 2 | Other Assets | Interest Rate Contracts    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Derivative Assets 369.4 361.2
Fair Value, Measurements, Recurring | LEVEL 2 | Other Liabilities    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Derivative Liabilities 4,514.9 5,131.2
Fair Value, Measurements, Recurring | LEVEL 2 | Other Liabilities | Foreign Exchange Contracts    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Derivative Liabilities 4,112.3 4,709.8
Fair Value, Measurements, Recurring | LEVEL 2 | Other Liabilities | Interest Rate Contracts    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Derivative Liabilities 402.6 421.4
Fair Value, Measurements, Recurring | LEVEL 2 | Other Liabilities | Other Financial Derivatives    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Derivative Liabilities 0.0 0.0
Fair Value, Measurements, Recurring | LEVEL 3    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Available for Sale 0.0 0.0
Fair Value, Measurements, Recurring | LEVEL 3 | U.S. Government    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Available for Sale 0.0 0.0
Fair Value, Measurements, Recurring | LEVEL 3 | Obligations of States and Political Subdivisions    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Available for Sale 0.0 0.0
Fair Value, Measurements, Recurring | LEVEL 3 | Government Sponsored Agency    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Available for Sale 0.0 0.0
Fair Value, Measurements, Recurring | LEVEL 3 | Non-U.S. Government    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Available for Sale 0.0 0.0
Fair Value, Measurements, Recurring | LEVEL 3 | Corporate Debt    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Available for Sale 0.0 0.0
Fair Value, Measurements, Recurring | LEVEL 3 | Covered Bonds    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Available for Sale 0.0 0.0
Fair Value, Measurements, Recurring | LEVEL 3 | Sub-Sovereign, Supranational and Non-U.S. Agency Bonds    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Available for Sale 0.0 0.0
Fair Value, Measurements, Recurring | LEVEL 3 | Other Asset-Backed    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Available for Sale 0.0 0.0
Fair Value, Measurements, Recurring | LEVEL 3 | Commercial Mortgage-Backed    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Available for Sale 0.0 0.0
Fair Value, Measurements, Recurring | LEVEL 3 | Other Assets    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Equity Securities 0.0 0.0
Derivative Assets 0.0 0.0
Fair Value, Measurements, Recurring | LEVEL 3 | Other Assets | Foreign Exchange Contracts    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Derivative Assets 0.0 0.0
Fair Value, Measurements, Recurring | LEVEL 3 | Other Assets | Interest Rate Contracts    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Derivative Assets 0.0 0.0
Fair Value, Measurements, Recurring | LEVEL 3 | Other Liabilities    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Derivative Liabilities 22.8 27.2
Fair Value, Measurements, Recurring | LEVEL 3 | Other Liabilities | Foreign Exchange Contracts    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Derivative Liabilities 0.0 0.0
Fair Value, Measurements, Recurring | LEVEL 3 | Other Liabilities | Interest Rate Contracts    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Derivative Liabilities 0.0 0.0
Fair Value, Measurements, Recurring | LEVEL 3 | Other Liabilities | Other Financial Derivatives    
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]    
Derivative Liabilities $ 22.8 $ 27.2