Securities (Narrative) (Details)	6 Months Ended
	Jun. 30, 2024 USD ($) Security	Jun. 30, 2023 USD ($)	Dec. 31, 2023 USD ($) Security
Debt and Equity Securities, FV-NI [Line Items]
Securities with an aggregate fair value	$ 4,666,648,000		$ 4,276,643,000
Securities available for sale, amortized cost	5,605,849,000		5,496,718,000
Securities classified as trading	0		$ 0
Sales of securities	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	732		698
Asset Pledged as Collateral without Right [Member]
Debt and Equity Securities, FV-NI [Line Items]
Securities pledged as collateral	$ 3,600,000,000		$ 4,700,000,000
Available for Sale and Held to Maturity [Member]
Debt and Equity Securities, FV-NI [Line Items]
Amortized cost of securities excluding accrued interest	$ 28,300,000		$ 27,400,000