Securities (Narrative) (Details)	3 Months Ended		9 Months Ended
	Sep. 30, 2024 USD ($) security	Jun. 30, 2024 USD ($)	Sep. 30, 2024 USD ($) security	Sep. 30, 2023 USD ($)	Dec. 31, 2023 USD ($) security
Debt and Equity Securities, FV-NI [Line Items]
Private mortgage-backed security fair value	$ 700,000		$ 700,000		$ 700,000
Debt securities, available-for-sale and held-to-maturity, number of positions | security	620		620		657
Number of securities held in an unrealized loss position | security	586		586		632
Investment securities, pledged as collateral for public deposits	$ 924,800,000		$ 924,800,000		$ 971,300,000
Gain on sale of VISA B shares		$ 4,500,000
Proceeds from sales of securities available for sale		138,200,000	138,182,000	$ 111,863,000
Securities losses, net		(4,700,000)
Proceeds from maturities, calls and principal repayments of securities available for sale		5,200,000	204,848,000	$ 133,341,000
Losses on calls of securities, net		$ (975,000)
FHLB stock and FRB stock, cost	41,200,000		41,200,000		54,500,000
FHLB, cost	8,500,000		8,500,000		21,700,000
FRB stock	32,700,000		32,700,000		32,800,000
Collateral For FRB Borrowings
Debt and Equity Securities, FV-NI [Line Items]
Investment securities, pledged as collateral for public deposits	582,600,000		$ 582,600,000		$ 679,000,000.0
Common Class B
Debt and Equity Securities, FV-NI [Line Items]
Gain on sale of VISA B shares	$ 4,500,000