v3.25.2
Investment Securities - Maturities of Investment Securities (Details) - USD ($)
$ in Millions
Jun. 30, 2025
Dec. 31, 2024
Available-for-Sale, Amortized Cost    
Available-for-Sale Amortized Cost, Within One Year $ 103.7  
Available-for-Sale Amortized Cost, After One Year but Within Five Years 1,296.0  
Available-for-Sale Amortized Cost, After Five Years but Within Ten Years 1,318.2  
Available-for-Sale Amortized Cost, After Ten Years 2,326.6  
Amortized Cost 5,044.5 $ 5,474.8
Available-for-Sale, Estimated Fair Value    
Available-for-Sale Estimated Fair Value, Within One Year 102.4  
Available-for-Sale Estimated Fair Value, After One Year but Within Five Years 1,244.0  
Available-for-Sale Estimated Fair Value, After Five Years but Within Ten Years 1,247.7  
Available-for-Sale Estimated Fair Value, After Ten Years 2,148.1  
Estimated Fair Value 4,742.2 5,057.1
Held-to-Maturity, Amortized Cost    
Held-to-Maturity Amortized Cost, Within One Year 108.1  
Held-to-Maturity Amortized Cost, After One Year but Within Five Years 446.6  
Held-to-Maturity Amortized Cost, After Five Years but Within Ten Years 442.0  
Held-to-Maturity Amortized Cost, After Ten Years 1,574.0  
Amortized Cost(1) 2,570.7 2,688.4
Held-to-Maturity, Estimated Fair Value    
Held-to-Maturity Estimated Fair Value, Within One Year 108.0  
Held-to-Maturity Estimated Fair Value, After One Year but Within Five Years 427.8  
Held-to-Maturity Estimated Fair Value, After Five Years but Within Ten Years 397.8  
Held-to-Maturity Estimated Fair Value, After Ten Years 1,383.4  
Investment debt securities held-to-maturity 2,317.0 2,358.6
Securities Sold under Agreements to Repurchase [Abstract]    
Securities Sold under Agreements to Repurchase, Fair Value of Collateral 3,315.7 3,460.2
Securities Loaned or Sold under Agreements to Repurchase, Fair Value Disclosure 3,049.9 $ 3,092.6
Investment Securities, Primarily Classified As Available-For-Sale, Callable, Within One Year, Fair Value 1,031.2  
Investment Securities, Primarily Classified As Available-For-Sale, Callable, Within One Year, Amortized Cost Basis $ 1,064.8