Loans and Allowance for Credit Losses (Narrative) (Details) $ in Thousands	3 Months Ended	9 Months Ended		12 Months Ended
	Dec. 31, 2021	Sep. 30, 2021 USD ($) loan	Sep. 30, 2020 USD ($) loan	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020 USD ($)
Accounts Notes And Loans Receivable [Line Items]
Accrued interest		$ 70,500					$ 76,200
Weighted average percentage of forecast		50.00%
Build back better infrastructure and social legislation package forecasted amount		$ 2,500,000,000
Nonaccrual loans		60,357					139,879
TDRs both accruing and nonaccruing		10,300					25,800
Unfunded commitment to borrowers related to modified TDR		0					4,600
Troubled Debt Restructurings [Member]
Accounts Notes And Loans Receivable [Line Items]
Nonaccrual loans		7,200					21,600
Reduced interest rate			$ 1,100
Troubled Debt Restructurings [Member] | Loans With Extended Amortization Terms Or Other Payment Concessions [Member]
Accounts Notes And Loans Receivable [Line Items]
Extended terms and other payment concessions		7,100	700
Troubled Debt Restructurings [Member] | Loans With Other Modifications [Member]
Accounts Notes And Loans Receivable [Line Items]
Other modifications		$ 500	2,100
Troubled Debt Restructurings [Member] | Loans With Significant Covenant Waivers [Member]
Accounts Notes And Loans Receivable [Line Items]
Covenant waivers			$ 400
Downside Scenario S-2 [Member]
Accounts Notes And Loans Receivable [Line Items]
Weighted average percentage of forecast		50.00%
Forecast [Member]
Accounts Notes And Loans Receivable [Line Items]
Unemployment percentage rate forecast	4.50%			3.50%	3.60%	5.50%
Gross domestic product weighted average				2.30%	4.30%	6.00%
Federal reserve rate				0.00%
Residential Mortgages [Member]
Accounts Notes And Loans Receivable [Line Items]
Nonaccrual loans		$ 25,964					40,573
Residential Mortgages [Member] | Troubled Debt Restructurings [Member]
Accounts Notes And Loans Receivable [Line Items]
Number of TDRs subsequently defaulted | loan		1	1
Recorded Investment		$ 600	$ 600
Commercial Non-Real Estate [Member] | Troubled Debt Restructurings [Member]
Accounts Notes And Loans Receivable [Line Items]
Number of TDRs subsequently defaulted | loan			1
Recorded Investment			$ 400
Consumer [Member]
Accounts Notes And Loans Receivable [Line Items]
Nonaccrual loans		12,238					23,385
Real estate in process of foreclosure		6,100					17,200
Real estate acquired through foreclosure		4,000					3,400
Consumer [Member] | Troubled Debt Restructurings [Member]
Accounts Notes And Loans Receivable [Line Items]
Number of TDRs subsequently defaulted | loan			2
Recorded Investment			$ 200
Total Commercial And Industrial [Member] | Total Commercial [Member]
Accounts Notes And Loans Receivable [Line Items]
Nonaccrual loans		16,668					66,692
Commercial Non-Real Estate [Member]
Accounts Notes And Loans Receivable [Line Items]
Paycheck protection program loans		$ 935,300					2,000,000
Commercial Non-Real Estate [Member] | Total Commercial And Industrial [Member] | Total Commercial [Member]
Accounts Notes And Loans Receivable [Line Items]
Loans interest bearing rate		1.00%
Loans receivable percentage of origination fee description		These loans also earn an origination fee of 1%, 3%, or 5%, depending on the loan size
Nonaccrual loans		$ 9,948					$ 52,836
Commercial Non-Real Estate [Member] | Total Commercial And Industrial [Member] | Minimum [Member] | Total Commercial [Member]
Accounts Notes And Loans Receivable [Line Items]
Loans term		2 years
Loans percentage of origination fee		1.00%
Commercial Non-Real Estate [Member] | Total Commercial And Industrial [Member] | Maximum [Member] | Total Commercial [Member]
Accounts Notes And Loans Receivable [Line Items]
Loans term		5 years
Loans percentage of origination fee		5.00%