Loans and Allowance for Credit Losses (Credit Quality Indicators by Segment and Portfolio Class) (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Total Commercial [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	$ 18,799,311	$ 18,444,094
Total Commercial [Member] | Total Commercial And Industrial [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	13,156,912	13,179,511
Total Commercial [Member] | Pass [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	18,127,211	17,684,578
Total Commercial [Member] | Pass [Member] | Total Commercial And Industrial [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	12,664,047	12,553,174
Total Commercial [Member] | Pass-Watch [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	396,983	457,620
Total Commercial [Member] | Pass-Watch [Member] | Total Commercial And Industrial [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	246,518	333,936
Total Commercial [Member] | Special Mention [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	61,600	90,253
Total Commercial [Member] | Special Mention [Member] | Total Commercial And Industrial [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	58,640	86,247
Total Commercial [Member] | Substandard [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	213,517	211,643
Total Commercial [Member] | Substandard [Member] | Total Commercial And Industrial [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	187,707	206,154
Residential Mortgages [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	3,721,106	3,092,605
Residential Mortgages [Member] | Performing [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	3,694,201	3,066,319
Residential Mortgages [Member] | Nonperforming [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	26,905	26,286
Consumer [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	1,463,262	1,577,347
Consumer [Member] | Performing [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	1,455,462	1,570,186
Consumer [Member] | Nonperforming [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	7,800	7,161
Residential Mortgage and Consumer [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	5,184,368	4,669,952
Residential Mortgage and Consumer [Member] | Performing [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	5,149,663	4,636,505
Residential Mortgage and Consumer [Member] | Nonperforming [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	34,705	33,447
Commercial Non-Real Estate [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	10,075,585	10,146,453
Commercial Non-Real Estate [Member] | Pass [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	9,680,970	9,641,117
Commercial Non-Real Estate [Member] | Pass-Watch [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	183,257	284,843
Commercial Non-Real Estate [Member] | Special Mention [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	50,128	79,980
Commercial Non-Real Estate [Member] | Substandard [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	161,230	140,513
Commercial Non-Real Estate [Member] | Total Commercial [Member] | Total Commercial And Industrial [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	10,075,585	10,146,453
Commercial Non-Real Estate [Member] | Total Commercial [Member] | Pass [Member] | Total Commercial And Industrial [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	9,680,970	9,641,117
Commercial Non-Real Estate [Member] | Total Commercial [Member] | Pass-Watch [Member] | Total Commercial And Industrial [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	183,257	284,843
Commercial Non-Real Estate [Member] | Total Commercial [Member] | Special Mention [Member] | Total Commercial And Industrial [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	50,128	79,980
Commercial Non-Real Estate [Member] | Total Commercial [Member] | Substandard [Member] | Total Commercial And Industrial [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	161,230	140,513
Commercial Real Estate - Owner Occupied [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	3,081,327	3,033,058
Commercial Real Estate - Owner Occupied [Member] | Pass [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	2,983,077	2,912,057
Commercial Real Estate - Owner Occupied [Member] | Pass-Watch [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	63,261	49,093
Commercial Real Estate - Owner Occupied [Member] | Special Mention [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	8,512	6,267
Commercial Real Estate - Owner Occupied [Member] | Substandard [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	26,477	65,641
Commercial Real Estate - Owner Occupied [Member] | Total Commercial [Member] | Total Commercial And Industrial [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	3,081,327	3,033,058
Commercial Real Estate - Owner Occupied [Member] | Total Commercial [Member] | Pass [Member] | Total Commercial And Industrial [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	2,983,077	2,912,057
Commercial Real Estate - Owner Occupied [Member] | Total Commercial [Member] | Pass-Watch [Member] | Total Commercial And Industrial [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	63,261	49,093
Commercial Real Estate - Owner Occupied [Member] | Total Commercial [Member] | Special Mention [Member] | Total Commercial And Industrial [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	8,512	6,267
Commercial Real Estate - Owner Occupied [Member] | Total Commercial [Member] | Substandard [Member] | Total Commercial And Industrial [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	26,477	65,641
Commercial Real Estate - Income Producing [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	4,027,553	3,560,991
Commercial Real Estate - Income Producing [Member] | Pass [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	3,862,680	3,440,648
Commercial Real Estate - Income Producing [Member] | Pass-Watch [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	137,577	111,587
Commercial Real Estate - Income Producing [Member] | Special Mention [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	2,258	3,810
Commercial Real Estate - Income Producing [Member] | Substandard [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	25,038	4,946
Commercial Real Estate - Income Producing [Member] | Total Commercial [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	4,027,553	3,560,991
Commercial Real Estate - Income Producing [Member] | Total Commercial [Member] | Pass [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	3,862,680	3,440,648
Commercial Real Estate - Income Producing [Member] | Total Commercial [Member] | Pass-Watch [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	137,577	111,587
Commercial Real Estate - Income Producing [Member] | Total Commercial [Member] | Special Mention [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	2,258	3,810
Commercial Real Estate - Income Producing [Member] | Total Commercial [Member] | Substandard [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	25,038	4,946
Construction and Land Development [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	1,614,846	1,703,592
Construction and Land Development [Member] | Pass [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	1,600,484	1,690,756
Construction and Land Development [Member] | Pass-Watch [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	12,888	12,097
Construction and Land Development [Member] | Special Mention [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	702	196
Construction and Land Development [Member] | Substandard [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	772	543
Construction and Land Development [Member] | Total Commercial [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	1,614,846	1,703,592
Construction and Land Development [Member] | Total Commercial [Member] | Pass [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	1,600,484	1,690,756
Construction and Land Development [Member] | Total Commercial [Member] | Pass-Watch [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	12,888	12,097
Construction and Land Development [Member] | Total Commercial [Member] | Special Mention [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	702	196
Construction and Land Development [Member] | Total Commercial [Member] | Substandard [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	$ 772	$ 543