Loans - Financing Receivables, Modified Loans Past Due in Excess of 90 Days or on Non-Accrual Status at Period-End (Details) - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022	Jun. 30, 2022
Financing Receivable, Troubled Debt Restructuring [Line Items]
Loans, net of unearned discounts	$ 17,746,311	$ 17,154,969
Payment Deferral
Financing Receivable, Troubled Debt Restructuring [Line Items]
Loans, net of unearned discounts	0		$ 1,116
Payment Deferral | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Financing Receivable, Troubled Debt Restructuring [Line Items]
Loans, net of unearned discounts	0		1,116
Combination: Payment Delay and Term Extention
Financing Receivable, Troubled Debt Restructuring [Line Items]
Loans, net of unearned discounts	36,486		0
Combination: Payment Delay and Term Extention | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Financing Receivable, Troubled Debt Restructuring [Line Items]
Loans, net of unearned discounts	36,486		0
Extended Maturity | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Financing Receivable, Troubled Debt Restructuring [Line Items]
Loans, net of unearned discounts	0		0
Commercial Real Estate Buildings Land And Other Loans [Member]
Financing Receivable, Troubled Debt Restructuring [Line Items]
Loans, net of unearned discounts	6,924,896	6,706,078
Commercial Real Estate Buildings Land And Other Loans [Member] | Payment Deferral
Financing Receivable, Troubled Debt Restructuring [Line Items]
Loans, net of unearned discounts	0		1,116
Commercial Real Estate Buildings Land And Other Loans [Member] | Payment Deferral | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Financing Receivable, Troubled Debt Restructuring [Line Items]
Loans, net of unearned discounts	0		1,116
Commercial Real Estate Buildings Land And Other Loans [Member] | Payment Deferral | Charge-offs
Financing Receivable, Troubled Debt Restructuring [Line Items]
Loans, net of unearned discounts	0		371
Commercial Real Estate Buildings Land And Other Loans [Member] | Payment Deferral | Proceeds from sales
Financing Receivable, Troubled Debt Restructuring [Line Items]
Loans, net of unearned discounts	0		0
Commercial Real Estate Buildings Land And Other Loans [Member] | Combination: Payment Delay and Term Extention
Financing Receivable, Troubled Debt Restructuring [Line Items]
Loans, net of unearned discounts	20,466		0
Commercial Real Estate Buildings Land And Other Loans [Member] | Combination: Payment Delay and Term Extention | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Financing Receivable, Troubled Debt Restructuring [Line Items]
Loans, net of unearned discounts	20,466		0
Commercial Real Estate Buildings Land And Other Loans [Member] | Combination: Payment Delay and Term Extention | Charge-offs
Financing Receivable, Troubled Debt Restructuring [Line Items]
Loans, net of unearned discounts	0		352
Commercial Real Estate Buildings Land And Other Loans [Member] | Combination: Payment Delay and Term Extention | Proceeds from sales
Financing Receivable, Troubled Debt Restructuring [Line Items]
Loans, net of unearned discounts	0		1,070
Commercial Real Estate Buildings Land And Other Loans [Member] | Extended Maturity | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Financing Receivable, Troubled Debt Restructuring [Line Items]
Loans, net of unearned discounts	0		0
Commercial Real Estate Buildings Land And Other Loans [Member] | Extended Maturity | Charge-offs
Financing Receivable, Troubled Debt Restructuring [Line Items]
Loans, net of unearned discounts	0		0
Commercial Real Estate Buildings Land And Other Loans [Member] | Extended Maturity | Proceeds from sales
Financing Receivable, Troubled Debt Restructuring [Line Items]
Loans, net of unearned discounts	0		0
Commercial and Industrial Total Energy Loans [Member]
Financing Receivable, Troubled Debt Restructuring [Line Items]
Loans, net of unearned discounts	986,571	925,729
Commercial Portfolio Segment [Member]
Financing Receivable, Troubled Debt Restructuring [Line Items]
Loans, net of unearned discounts	5,726,804	$ 5,674,798
Commercial Portfolio Segment [Member] | Payment Deferral
Financing Receivable, Troubled Debt Restructuring [Line Items]
Loans, net of unearned discounts	0
Commercial Portfolio Segment [Member] | Payment Deferral | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Financing Receivable, Troubled Debt Restructuring [Line Items]
Loans, net of unearned discounts	0		0
Commercial Portfolio Segment [Member] | Combination: Payment Delay and Term Extention
Financing Receivable, Troubled Debt Restructuring [Line Items]
Loans, net of unearned discounts	16,020
Commercial Portfolio Segment [Member] | Combination: Payment Delay and Term Extention | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Financing Receivable, Troubled Debt Restructuring [Line Items]
Loans, net of unearned discounts	16,020		0
Commercial Portfolio Segment [Member] | Extended Maturity | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Financing Receivable, Troubled Debt Restructuring [Line Items]
Loans, net of unearned discounts	$ 0		$ 0