Loans and Allowance for Credit Losses (Aging Analysis of Past Due Loans by Portfolio Class) (Details) - USD ($) $ in Thousands	Sep. 30, 2024	Dec. 31, 2023	Sep. 30, 2023
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans	$ 23,455,587	$ 23,921,917	$ 23,983,679
Recorded Investment > 90 Days and Accruing	5,967	9,609
30-59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans	68,314	70,766
60-89 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans	26,875	22,881
Greater Than 90 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans	69,213	50,034
Total Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans	164,402	143,681
Current [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans	23,291,185	23,778,236
Total Commercial [Member] | Commercial Real Estate - Income Producing [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans	3,988,661	3,986,943	4,027,553
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	264	3,938
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	1,875	408
Total Commercial [Member] | Commercial Real Estate - Income Producing [Member] | Total Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans	2,139	4,952
Total Commercial [Member] | Commercial Real Estate - Income Producing [Member] | Current [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans	3,986,522	3,981,991
Total Commercial [Member] | Construction and Land Development [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans	1,423,615	1,551,091	1,614,846
Recorded Investment > 90 Days and Accruing	68	742
Total Commercial [Member] | Construction and Land Development [Member] | 30-59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans	528	1,655
Total Commercial [Member] | Construction and Land Development [Member] | 60-89 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans	338	1,220
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	2,534	1,208
Total Commercial [Member] | Construction and Land Development [Member] | Total Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans	3,400	4,083
Total Commercial [Member] | Construction and Land Development [Member] | Current [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans	1,420,215	1,547,008
Total Commercial [Member] | Total Commercial And Industrial [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans	12,684,482	13,051,047	13,156,912
Recorded Investment > 90 Days and Accruing	2,194	6,213
Total Commercial [Member] | Total Commercial And Industrial [Member] | 30-59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans	46,051	13,925
Total Commercial [Member] | Total Commercial And Industrial [Member] | 60-89 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans	6,252	5,977
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	23,901	22,847
Total Commercial [Member] | Total Commercial And Industrial [Member] | Total Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans	76,204	42,749
Total Commercial [Member] | Total Commercial And Industrial [Member] | Current [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans	12,608,278	13,008,298
Total Commercial [Member] | Total Commercial And Industrial [Member] | Commercial Non-Real Estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans	9,588,309	9,957,284	10,075,585
Recorded Investment > 90 Days and Accruing	2,040	5,782
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	13,822	12,311
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	5,275	4,381
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	20,944	21,132
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	40,041	37,824
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	9,548,268	9,919,460
Total Commercial [Member] | Total Commercial And Industrial [Member] | Commercial Real Estate - Owner Occupied [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans	3,096,173	3,093,763	3,081,327
Recorded Investment > 90 Days and Accruing	154	431
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	32,229	1,614
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	977	1,596
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	2,957	1,715
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	36,163	4,925
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	3,060,010	3,088,838
Residential Mortgages [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans	3,988,309	3,886,072	3,721,106
Recorded Investment > 90 Days and Accruing	229	172
Residential Mortgages [Member] | 30-59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans	9,700	40,189
Residential Mortgages [Member] | 60-89 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans	14,821	9,121
Residential Mortgages [Member] | Greater Than 90 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans	30,618	18,960
Residential Mortgages [Member] | Total Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans	55,139	68,270
Residential Mortgages [Member] | Current [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans	3,933,170	3,817,802
Consumer [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans	1,370,520	1,446,764	$ 1,463,262
Recorded Investment > 90 Days and Accruing	3,476	2,482
Consumer [Member] | 30-59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans	11,771	11,059
Consumer [Member] | 60-89 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans	5,464	5,957
Consumer [Member] | Greater Than 90 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans	10,285	6,611
Consumer [Member] | Total Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans	27,520	23,627
Consumer [Member] | Current [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans	$ 1,343,000	1,423,137
Consumer [Member] | Commercial Real Estate - Income Producing [Member] | 60-89 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans		$ 606