v3.26.1
Available-for-Sale and Held-to-Maturity Securities (Narrative) (Details)
3 Months Ended
Mar. 31, 2026
USD ($)
Security
Mar. 31, 2025
USD ($)
Dec. 31, 2025
USD ($)
Security
Other Than Temporary Impairment Credit Losses Recognized In Earnings [Line Items]      
Accrued interest receivable $ 88,600,000   $ 90,700,000
Allowance for credit losses 0    
Proceeds from sale of available-for-sale securities 0 $ 0  
Financial instruments pledged as collateral $ 943,100,000   $ 880,500,000
Number of available for sale securities whose amortized costs exceeded their fair values | Security 217   204
Available-for-sale Securities, Continuous $ 116,935,000   $ 110,060,000
Available-for-sale Securities, Continuous Unrealized 111,827,000   108,681,000
Available-for-sale Securities, Continuous $ 1,309,346,000   $ 1,155,012,000
Percentage of available-for-sale portfolio 82.40%   72.50%
Percentage available for sale securities 88.00%    
Pledged [Member]      
Other Than Temporary Impairment Credit Losses Recognized In Earnings [Line Items]      
Trading securities pledged $ 3,500,000,000   $ 3,300,000,000
Other Asset [Member]      
Other Than Temporary Impairment Credit Losses Recognized In Earnings [Line Items]      
Accrued interest receivable $ 83,800,000   $ 84,100,000