Loans and Allowance for Credit Losses (Aging Analysis of Past Due Loans by Portfolio Class) (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022	Sep. 30, 2022
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans	$ 23,983,679	$ 23,114,046	$ 22,585,585
Recorded Investment > 90 Days and Accruing	24,170	4,585
30-59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans	46,448	65,080
60-89 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans	27,637	38,779
Greater Than 90 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans	59,329	28,372
Total Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans	133,414	132,231
Current [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans	23,850,265	22,981,815
Total Commercial [Member] | Commercial Real Estate - Income Producing [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans	4,027,553	3,560,991	3,686,540
Recorded Investment > 90 Days and Accruing	19,139
Total Commercial [Member] | Commercial Real Estate - Income Producing [Member] | 30-59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans	224	879
Total Commercial [Member] | Commercial Real Estate - Income Producing [Member] | 60-89 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans	300
Total Commercial [Member] | Commercial Real Estate - Income Producing [Member] | Greater Than 90 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans	19,428	1,174
Total Commercial [Member] | Commercial Real Estate - Income Producing [Member] | Total Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans	19,952	2,053
Total Commercial [Member] | Commercial Real Estate - Income Producing [Member] | Current [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans	4,007,601	3,558,938
Total Commercial [Member] | Construction and Land Development [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans	1,614,846	1,703,592	1,541,257
Recorded Investment > 90 Days and Accruing	67	54
Total Commercial [Member] | Construction and Land Development [Member] | 30-59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans	947	4,029
Total Commercial [Member] | Construction and Land Development [Member] | 60-89 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans	150	242
Total Commercial [Member] | Construction and Land Development [Member] | Greater Than 90 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans	148	133
Total Commercial [Member] | Construction and Land Development [Member] | Total Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans	1,245	4,404
Total Commercial [Member] | Construction and Land Development [Member] | Current [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans	1,613,601	1,699,188
Total Commercial [Member] | Total Commercial And Industrial [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans	13,156,912	13,179,511	12,938,560
Recorded Investment > 90 Days and Accruing	2,513	2,619
Total Commercial [Member] | Total Commercial And Industrial [Member] | 30-59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans	23,354	23,119
Total Commercial [Member] | Total Commercial And Industrial [Member] | 60-89 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans	14,741	24,675
Total Commercial [Member] | Total Commercial And Industrial [Member] | Greater Than 90 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans	15,846	5,312
Total Commercial [Member] | Total Commercial And Industrial [Member] | Total Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans	53,941	53,106
Total Commercial [Member] | Total Commercial And Industrial [Member] | Current [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans	13,102,971	13,126,405
Total Commercial [Member] | Total Commercial And Industrial [Member] | Commercial Non-Real Estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans	10,075,585	10,146,453	9,905,427
Recorded Investment > 90 Days and Accruing	1,476	996
Total Commercial [Member] | Total Commercial And Industrial [Member] | Commercial Non-Real Estate [Member] | 30-59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans	20,712	4,050
Total Commercial [Member] | Total Commercial And Industrial [Member] | Commercial Non-Real Estate [Member] | 60-89 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans	12,881	21,329
Total Commercial [Member] | Total Commercial And Industrial [Member] | Commercial Non-Real Estate [Member] | Greater Than 90 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans	13,522	3,418
Total Commercial [Member] | Total Commercial And Industrial [Member] | Commercial Non-Real Estate [Member] | Total Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans	47,115	28,797
Total Commercial [Member] | Total Commercial And Industrial [Member] | Commercial Non-Real Estate [Member] | Current [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans	10,028,470	10,117,656
Total Commercial [Member] | Total Commercial And Industrial [Member] | Commercial Real Estate - Owner Occupied [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans	3,081,327	3,033,058	3,033,133
Recorded Investment > 90 Days and Accruing	1,037	1,623
Total Commercial [Member] | Total Commercial And Industrial [Member] | Commercial Real Estate - Owner Occupied [Member] | 30-59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans	2,642	19,069
Total Commercial [Member] | Total Commercial And Industrial [Member] | Commercial Real Estate - Owner Occupied [Member] | 60-89 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans	1,860	3,346
Total Commercial [Member] | Total Commercial And Industrial [Member] | Commercial Real Estate - Owner Occupied [Member] | Greater Than 90 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans	2,324	1,894
Total Commercial [Member] | Total Commercial And Industrial [Member] | Commercial Real Estate - Owner Occupied [Member] | Total Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans	6,826	24,309
Total Commercial [Member] | Total Commercial And Industrial [Member] | Commercial Real Estate - Owner Occupied [Member] | Current [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans	3,074,501	3,008,749
Residential Mortgages [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans	3,721,106	3,092,605	2,843,723
Recorded Investment > 90 Days and Accruing	85	293
Residential Mortgages [Member] | 30-59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans	9,419	28,208
Residential Mortgages [Member] | 60-89 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans	8,834	11,056
Residential Mortgages [Member] | Greater Than 90 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans	17,878	17,346
Residential Mortgages [Member] | Total Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans	36,131	56,610
Residential Mortgages [Member] | Current [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans	3,684,975	3,035,995
Consumer [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans	1,463,262	1,577,347	$ 1,575,505
Recorded Investment > 90 Days and Accruing	2,366	1,619
Consumer [Member] | 30-59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans	12,504	8,845
Consumer [Member] | 60-89 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans	3,612	2,806
Consumer [Member] | Greater Than 90 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans	6,029	4,407
Consumer [Member] | Total Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans	22,145	16,058
Consumer [Member] | Current [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans	$ 1,441,117	$ 1,561,289