Loans and Allowance for Credit Losses (Loans, Net of Unearned Income) (Details) - USD ($) $ in Thousands	Jun. 30, 2022	Dec. 31, 2021	Jun. 30, 2021
Accounts Notes And Loans Receivable [Line Items]
Total loans	$ 21,846,068	$ 21,134,282	$ 21,148,530
Residential Mortgages [Member]
Accounts Notes And Loans Receivable [Line Items]
Total loans	2,615,807	2,423,890	2,412,459
Consumer [Member]
Accounts Notes And Loans Receivable [Line Items]
Total loans	1,570,725	1,583,390	1,679,429
Commercial Real Estate - Income Producing [Member] | Total Commercial [Member]
Accounts Notes And Loans Receivable [Line Items]
Total loans	3,641,243	3,464,626	3,419,028
Construction and Land Development [Member] | Total Commercial [Member]
Accounts Notes And Loans Receivable [Line Items]
Total loans	1,408,727	1,228,670	1,295,036
Total Commercial And Industrial [Member] | Total Commercial [Member]
Accounts Notes And Loans Receivable [Line Items]
Total loans	12,609,566	12,433,706	12,342,578
Total Commercial And Industrial [Member] | Commercial Non-Real Estate [Member] | Total Commercial [Member]
Accounts Notes And Loans Receivable [Line Items]
Total loans	9,645,092	9,612,460	9,532,710
Total Commercial And Industrial [Member] | Commercial Real Estate - Owner Occupied [Member] | Total Commercial [Member]
Accounts Notes And Loans Receivable [Line Items]
Total loans	$ 2,964,474	$ 2,821,246	$ 2,809,868