Securities (Narrative) (Details)	3 Months Ended
	Mar. 31, 2025 USD ($) Security	Mar. 31, 2024 USD ($)	Dec. 31, 2024 USD ($) Security
Debt and Equity Securities, FV-NI [Line Items]
Securities with an aggregate fair value	$ 4,204,882,000		$ 4,608,320,000
Securities available for sale, amortized cost	5,845,045,000		5,774,133,000
Securities classified as trading	0		$ 0
Gross gains	0	$ 0
Gross losses	0	$ 0
Allowance for credit loss	$ 0
Securities that met the criteria of a credit loss event | Security	0
Number of securities with market values below their cost basis | Security	673		729
Asset Pledged as Collateral without Right [Member]
Debt and Equity Securities, FV-NI [Line Items]
Securities pledged as collateral	$ 3,200,000,000		$ 3,900,000,000
Available for Sale and Held to Maturity [Member]
Debt and Equity Securities, FV-NI [Line Items]
Amortized cost of securities excluding accrued interest	$ 30,500,000		$ 29,800,000