v3.25.2
Securities (Remaining Maturity of Securities Available for Sale and Held to Maturity) (Details) - USD ($)
$ in Millions
Jun. 30, 2025
Dec. 31, 2024
Available for Sale - Amortized Cost    
ONE YEAR OR LESS $ 5,147.8  
ONE TO FIVE YEARS 22,162.6  
FIVE TO TEN YEARS 3,868.9  
OVER TEN YEARS 1,190.6  
AMORTIZED COST 32,369.9 $ 29,229.1
Available for Sale - Fair Value    
ONE YEAR OR LESS 5,121.5  
ONE TO FIVE YEARS 22,128.2  
FIVE TO TEN YEARS 3,830.2  
OVER TEN YEARS 1,170.5  
Fair Value 32,250.4 29,001.5
Held to Maturity - Amortized Cost    
ONE YEAR OR LESS 6,250.9  
ONE TO FIVE YEARS 10,133.0  
FIVE TO TEN YEARS 3,229.7  
OVER TEN YEARS 1,787.2  
AMORTIZED COST 21,400.8 22,296.7
Held to Maturity - Fair Value    
ONE YEAR OR LESS 6,136.5  
ONE TO FIVE YEARS 9,607.6  
FIVE TO TEN YEARS 2,950.1  
OVER TEN YEARS 1,446.8  
Fair Value 20,141.0 20,654.5
Amortized Cost    
ONE YEAR OR LESS 11,398.7  
ONE TO FIVE YEARS 32,295.6  
FIVE TO TEN YEARS 7,098.6  
OVER TEN YEARS 2,977.8  
AMORTIZED COST 53,770.7 51,525.8
Fair Value    
ONE YEAR OR LESS 11,258.0  
ONE TO FIVE YEARS 31,735.8  
FIVE TO TEN YEARS 6,780.3  
OVER TEN YEARS 2,617.3  
FAIR VALUE 52,391.4 49,656.0
U.S. Government    
Available for Sale - Amortized Cost    
ONE YEAR OR LESS 348.2  
ONE TO FIVE YEARS 7,225.9  
FIVE TO TEN YEARS 714.0  
OVER TEN YEARS 0.0  
AMORTIZED COST 8,288.1 7,388.9
Available for Sale - Fair Value    
ONE YEAR OR LESS 347.2  
ONE TO FIVE YEARS 7,226.3  
FIVE TO TEN YEARS 712.5  
OVER TEN YEARS 0.0  
Fair Value 8,286.0 7,367.5
Obligations of States and Political Subdivisions    
Available for Sale - Amortized Cost    
ONE YEAR OR LESS 0.0  
ONE TO FIVE YEARS 249.1  
FIVE TO TEN YEARS 71.7  
OVER TEN YEARS 0.0  
AMORTIZED COST 320.8 311.2
Available for Sale - Fair Value    
ONE YEAR OR LESS 0.0  
ONE TO FIVE YEARS 238.7  
FIVE TO TEN YEARS 68.1  
OVER TEN YEARS 0.0  
Fair Value 306.8 297.6
Held to Maturity - Amortized Cost    
ONE YEAR OR LESS 173.5  
ONE TO FIVE YEARS 1,425.2  
FIVE TO TEN YEARS 827.7  
OVER TEN YEARS 102.6  
AMORTIZED COST 2,529.0 2,548.2
Held to Maturity - Fair Value    
ONE YEAR OR LESS 173.0  
ONE TO FIVE YEARS 1,418.0  
FIVE TO TEN YEARS 807.6  
OVER TEN YEARS 98.2  
Fair Value 2,496.8 2,458.9
Government Sponsored Agency    
Available for Sale - Amortized Cost    
ONE YEAR OR LESS 3,711.2  
ONE TO FIVE YEARS 8,781.4  
FIVE TO TEN YEARS 2,327.9  
OVER TEN YEARS 1,109.3  
AMORTIZED COST 15,929.8 13,410.5
Available for Sale - Fair Value    
ONE YEAR OR LESS 3,693.8  
ONE TO FIVE YEARS 8,749.7  
FIVE TO TEN YEARS 2,306.5  
OVER TEN YEARS 1,088.9  
Fair Value 15,838.9 13,288.9
Held to Maturity - Amortized Cost    
ONE YEAR OR LESS 928.9  
ONE TO FIVE YEARS 3,757.5  
FIVE TO TEN YEARS 2,259.7  
OVER TEN YEARS 1,497.4  
AMORTIZED COST 8,443.5 8,635.0
Held to Maturity - Fair Value    
ONE YEAR OR LESS 851.7  
ONE TO FIVE YEARS 3,432.1  
FIVE TO TEN YEARS 2,013.4  
OVER TEN YEARS 1,294.7  
Fair Value 7,591.9 7,554.6
Non-U.S. Government    
Available for Sale - Amortized Cost    
ONE YEAR OR LESS 122.3  
ONE TO FIVE YEARS 197.7  
FIVE TO TEN YEARS 0.0  
OVER TEN YEARS 0.0  
AMORTIZED COST 320.0 308.9
Available for Sale - Fair Value    
ONE YEAR OR LESS 120.8  
ONE TO FIVE YEARS 192.4  
FIVE TO TEN YEARS 0.0  
OVER TEN YEARS 0.0  
Fair Value 313.2 296.8
Held to Maturity - Amortized Cost    
ONE YEAR OR LESS 1,880.5  
ONE TO FIVE YEARS 995.9  
FIVE TO TEN YEARS 0.0  
OVER TEN YEARS 0.0  
AMORTIZED COST 2,876.4 3,735.8
Held to Maturity - Fair Value    
ONE YEAR OR LESS 1,873.8  
ONE TO FIVE YEARS 963.5  
FIVE TO TEN YEARS 0.0  
OVER TEN YEARS 0.0  
Fair Value 2,837.3 3,679.7
Corporate Debt    
Available for Sale - Amortized Cost    
ONE YEAR OR LESS 94.5  
ONE TO FIVE YEARS 0.0  
FIVE TO TEN YEARS 0.0  
OVER TEN YEARS 0.0  
AMORTIZED COST 94.5 166.6
Available for Sale - Fair Value    
ONE YEAR OR LESS 93.4  
ONE TO FIVE YEARS 0.0  
FIVE TO TEN YEARS 0.0  
OVER TEN YEARS 0.0  
Fair Value 93.4 163.8
Held to Maturity - Amortized Cost    
ONE YEAR OR LESS 168.1  
ONE TO FIVE YEARS 129.4  
FIVE TO TEN YEARS 0.0  
OVER TEN YEARS 0.0  
AMORTIZED COST 297.5 351.6
Held to Maturity - Fair Value    
ONE YEAR OR LESS 167.2  
ONE TO FIVE YEARS 123.3  
FIVE TO TEN YEARS 0.0  
OVER TEN YEARS 0.0  
Fair Value 290.5 340.6
Covered Bonds    
Available for Sale - Amortized Cost    
ONE YEAR OR LESS 0.0  
ONE TO FIVE YEARS 237.2  
FIVE TO TEN YEARS 0.0  
OVER TEN YEARS 0.0  
AMORTIZED COST 237.2 234.0
Available for Sale - Fair Value    
ONE YEAR OR LESS 0.0  
ONE TO FIVE YEARS 235.5  
FIVE TO TEN YEARS 0.0  
OVER TEN YEARS 0.0  
Fair Value 235.5 230.9
Held to Maturity - Amortized Cost    
ONE YEAR OR LESS 264.1  
ONE TO FIVE YEARS 1,188.5  
FIVE TO TEN YEARS 89.1  
OVER TEN YEARS 0.0  
AMORTIZED COST 1,541.7 1,776.8
Held to Maturity - Fair Value    
ONE YEAR OR LESS 263.5  
ONE TO FIVE YEARS 1,138.7  
FIVE TO TEN YEARS 88.2  
OVER TEN YEARS 0.0  
Fair Value 1,490.4 1,714.7
Certificates of Deposit    
Held to Maturity - Amortized Cost    
ONE YEAR OR LESS 536.2  
ONE TO FIVE YEARS 0.0  
FIVE TO TEN YEARS 0.0  
OVER TEN YEARS 0.0  
AMORTIZED COST 536.2 336.0
Held to Maturity - Fair Value    
ONE YEAR OR LESS 536.0  
ONE TO FIVE YEARS 0.0  
FIVE TO TEN YEARS 0.0  
OVER TEN YEARS 0.0  
Fair Value 536.0 335.7
Sub-Sovereign, Supranational and Non-U.S. Agency Bonds    
Available for Sale - Amortized Cost    
ONE YEAR OR LESS 664.8  
ONE TO FIVE YEARS 3,998.4  
FIVE TO TEN YEARS 301.0  
OVER TEN YEARS 0.0  
AMORTIZED COST 4,964.2 4,617.0
Available for Sale - Fair Value    
ONE YEAR OR LESS 663.5  
ONE TO FIVE YEARS 4,014.7  
FIVE TO TEN YEARS 292.7  
OVER TEN YEARS 0.0  
Fair Value 4,970.9 4,583.1
Held to Maturity - Amortized Cost    
ONE YEAR OR LESS 2,235.9  
ONE TO FIVE YEARS 2,270.9  
FIVE TO TEN YEARS 6.0  
OVER TEN YEARS 0.0  
AMORTIZED COST 4,512.8 4,146.9
Held to Maturity - Fair Value    
ONE YEAR OR LESS 2,208.9  
ONE TO FIVE YEARS 2,195.8  
FIVE TO TEN YEARS 5.1  
OVER TEN YEARS 0.0  
Fair Value 4,409.8 3,977.0
Other Asset-Backed    
Available for Sale - Amortized Cost    
ONE YEAR OR LESS 153.7  
ONE TO FIVE YEARS 1,032.0  
FIVE TO TEN YEARS 420.7  
OVER TEN YEARS 81.3  
AMORTIZED COST 1,687.7 2,188.6
Available for Sale - Fair Value    
ONE YEAR OR LESS 150.1  
ONE TO FIVE YEARS 1,034.0  
FIVE TO TEN YEARS 422.2  
OVER TEN YEARS 81.6  
Fair Value 1,687.9 2,182.7
Held to Maturity - Amortized Cost    
AMORTIZED COST   107.1
Held to Maturity - Fair Value    
Fair Value   107.3
Commercial Mortgage-Backed    
Available for Sale - Amortized Cost    
ONE YEAR OR LESS 53.1  
ONE TO FIVE YEARS 440.9  
FIVE TO TEN YEARS 33.6  
OVER TEN YEARS 0.0  
AMORTIZED COST 527.6 603.4
Available for Sale - Fair Value    
ONE YEAR OR LESS 52.7  
ONE TO FIVE YEARS 436.9  
FIVE TO TEN YEARS 28.2  
OVER TEN YEARS 0.0  
Fair Value 517.8 590.2
Held to Maturity - Amortized Cost    
ONE YEAR OR LESS 0.0  
ONE TO FIVE YEARS 37.6  
FIVE TO TEN YEARS 0.0  
OVER TEN YEARS 0.0  
AMORTIZED COST 37.6 37.6
Held to Maturity - Fair Value    
ONE YEAR OR LESS 0.0  
ONE TO FIVE YEARS 36.4  
FIVE TO TEN YEARS 0.0  
OVER TEN YEARS 0.0  
Fair Value 36.4 36.8
Other    
Held to Maturity - Amortized Cost    
ONE YEAR OR LESS 63.7  
ONE TO FIVE YEARS 328.0  
FIVE TO TEN YEARS 47.2  
OVER TEN YEARS 187.2  
AMORTIZED COST 626.1 621.7
Held to Maturity - Fair Value    
ONE YEAR OR LESS 62.4  
ONE TO FIVE YEARS 299.8  
FIVE TO TEN YEARS 35.8  
OVER TEN YEARS 53.9  
Fair Value $ 451.9 $ 449.2