Loans and Allowance for Credit Losses (Narrative) (Details)	3 Months Ended	9 Months Ended	12 Months Ended
	Sep. 30, 2023 USD ($) Loan	Sep. 30, 2023 USD ($) Loan	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023	Jul. 03, 2023 USD ($)	Dec. 31, 2022 USD ($)	Sep. 30, 2022
Accounts Notes And Loans Receivable [Line Items]
Accrued interest	$ 118,900,000	$ 118,900,000					$ 100,200,000
Weighted average percentage of forecast								25.00%
Base line economic forecast probability percentage		40.00%
Description of post modification defaults		A payment default occurs if the loan is either 90 days or more delinquent or has been charged off as of the end of the period presented.
Nonaccrual loans	60,331,000	$ 60,331,000					38,991,000
Unfunded commitment to borrowers related to MEFD or TDR	0	0					0
Loans held for sale	15,862,000	15,862,000					26,385,000
LIBOR Transition [Member]
Accounts Notes And Loans Receivable [Line Items]
Loans receivable						$ 3,100,000,000
Troubled Debt Restructurings [Member]
Accounts Notes And Loans Receivable [Line Items]
Nonaccrual loans							2,600,000
Accruing and nonaccruing							4,500,000
Modified Loans To Borrowers Experiencing Financial Difficulty [Member]
Accounts Notes And Loans Receivable [Line Items]
Nonaccrual loans	20,000	20,000
Accruing and nonaccruing	28,900,000	$ 28,900,000
Slower Near-term Growth/Mild Recessionary Scenario S-2 [Member]
Accounts Notes And Loans Receivable [Line Items]
Allowance for credit losses probability weighting percentage		60.00%
Unemployment percentage rate forecast			4.90%	6.10%	3.90%
Gross domestic product annual growth percentage			2.50%	(0.20%)	2.10%
Mild Recessionary Scenario S-2 [Member]
Accounts Notes And Loans Receivable [Line Items]
Description of decline in gross domestic product due to mild recession		This leads to a mild recession that starts in the fourth quarter of 2023 lasting three quarters, with the stock market contracting 22%.
Stock market contracting percentage		22.00%
Downside Scenario S-2 [Member]
Accounts Notes And Loans Receivable [Line Items]
Weighted average percentage of forecast								75.00%
Forecast [Member]
Accounts Notes And Loans Receivable [Line Items]
Unemployment percentage rate forecast			4.20%	4.10%	3.70%
Gross domestic product annual growth percentage			1.90%	1.40%	2.10%
Residential Mortgages [Member]
Accounts Notes And Loans Receivable [Line Items]
Nonaccrual loans	26,905,000	$ 26,905,000					25,269,000
Loans carried at fair value option	13,300,000	13,300,000					10,800,000
Unpaid principal balance	13,100,000	13,100,000					10,600,000
Consumer [Member]
Accounts Notes And Loans Receivable [Line Items]
Nonaccrual loans	$ 7,800,000	$ 7,800,000					6,692,000
Number of contracts subsequently defaulted | Loan	1	1
Recorded Investment	$ 20,000	$ 20,000
Real estate in process of foreclosure	5,400,000	5,400,000					4,900,000
Real estate acquired through foreclosure	$ 1,400,000	$ 1,400,000					400,000
Weighted Average [Member] | Other Than Insignificant Payment Delays [Member]
Accounts Notes And Loans Receivable [Line Items]
Reportable modification period		4 months
Weighted Average [Member] | Total Commercial [Member] | Term Extension [Member]
Accounts Notes And Loans Receivable [Line Items]
Reportable modification period	8 months	8 months
Weighted Average [Member] | Residential Mortgages [Member] | Term Extension [Member]
Accounts Notes And Loans Receivable [Line Items]
Reportable modification period	15 years	15 years
Weighted Average [Member] | Consumer [Member] | Term Extension [Member]
Accounts Notes And Loans Receivable [Line Items]
Reportable modification period	5 years	5 years
Total Commercial And Industrial [Member] | Total Commercial [Member]
Accounts Notes And Loans Receivable [Line Items]
Nonaccrual loans	$ 24,540,000	$ 24,540,000					5,481,000
Commercial Non-Real Estate [Member] | Total Commercial And Industrial [Member] | Total Commercial [Member]
Accounts Notes And Loans Receivable [Line Items]
Nonaccrual loans	$ 22,108,000	$ 22,108,000					$ 4,020,000