Loans and Allowance for Credit Losses (Credit Quality Indicators by Segment and Portfolio Class) (Details) - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022
Total Commercial [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	$ 18,703,441	$ 18,444,094
Total Commercial [Member] | Total Commercial And Industrial [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	13,172,761	13,179,511
Total Commercial [Member] | Pass [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	17,981,958	17,684,578
Total Commercial [Member] | Pass [Member] | Total Commercial And Industrial [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	12,586,456	12,553,174
Total Commercial [Member] | Pass-Watch [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	419,273	457,620
Total Commercial [Member] | Pass-Watch [Member] | Total Commercial And Industrial [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	309,966	333,936
Total Commercial [Member] | Special Mention [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	74,551	90,253
Total Commercial [Member] | Special Mention [Member] | Total Commercial And Industrial [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	55,239	86,247
Total Commercial [Member] | Substandard [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	227,659	211,643
Total Commercial [Member] | Substandard [Member] | Total Commercial And Industrial [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	221,100	206,154
Residential Mortgages [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	3,581,514	3,092,605
Residential Mortgages [Member] | Performing [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	3,554,056	3,066,319
Residential Mortgages [Member] | Nonperforming [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	27,458	26,286
Consumer [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	1,504,931	1,577,347
Consumer [Member] | Performing [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	1,497,458	1,570,186
Consumer [Member] | Nonperforming [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	7,473	7,161
Residential Mortgage and Consumer [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	5,086,445	4,669,952
Residential Mortgage and Consumer [Member] | Performing [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	5,051,514	4,636,505
Residential Mortgage and Consumer [Member] | Nonperforming [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	34,931	33,447
Commercial Non-Real Estate [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	10,113,932	10,146,453
Commercial Non-Real Estate [Member] | Pass [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	9,641,587	9,641,117
Commercial Non-Real Estate [Member] | Pass-Watch [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	254,542	284,843
Commercial Non-Real Estate [Member] | Special Mention [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	49,664	79,980
Commercial Non-Real Estate [Member] | Substandard [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	168,139	140,513
Commercial Non-Real Estate [Member] | Total Commercial [Member] | Total Commercial And Industrial [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	10,113,932	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	9,641,587	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	254,542	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	49,664	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	168,139	140,513
Commercial Real Estate - Owner Occupied [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	3,058,829	3,033,058
Commercial Real Estate - Owner Occupied [Member] | Pass [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	2,944,869	2,912,057
Commercial Real Estate - Owner Occupied [Member] | Pass-Watch [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	55,424	49,093
Commercial Real Estate - Owner Occupied [Member] | Special Mention [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	5,575	6,267
Commercial Real Estate - Owner Occupied [Member] | Substandard [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	52,961	65,641
Commercial Real Estate - Owner Occupied [Member] | Total Commercial [Member] | Total Commercial And Industrial [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	3,058,829	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	2,944,869	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	55,424	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	5,575	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	52,961	65,641
Commercial Real Estate - Income Producing [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	3,762,428	3,560,991
Commercial Real Estate - Income Producing [Member] | Pass [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	3,637,979	3,440,648
Commercial Real Estate - Income Producing [Member] | Pass-Watch [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	100,027	111,587
Commercial Real Estate - Income Producing [Member] | Special Mention [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	18,422	3,810
Commercial Real Estate - Income Producing [Member] | Substandard [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	6,000	4,946
Commercial Real Estate - Income Producing [Member] | Total Commercial [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	3,762,428	3,560,991
Commercial Real Estate - Income Producing [Member] | Total Commercial [Member] | Pass [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	3,637,979	3,440,648
Commercial Real Estate - Income Producing [Member] | Total Commercial [Member] | Pass-Watch [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	100,027	111,587
Commercial Real Estate - Income Producing [Member] | Total Commercial [Member] | Special Mention [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	18,422	3,810
Commercial Real Estate - Income Producing [Member] | Total Commercial [Member] | Substandard [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	6,000	4,946
Construction and Land Development [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	1,768,252	1,703,592
Construction and Land Development [Member] | Pass [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	1,757,523	1,690,756
Construction and Land Development [Member] | Pass-Watch [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	9,280	12,097
Construction and Land Development [Member] | Special Mention [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	890	196
Construction and Land Development [Member] | Substandard [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	559	543
Construction and Land Development [Member] | Total Commercial [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	1,768,252	1,703,592
Construction and Land Development [Member] | Total Commercial [Member] | Pass [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	1,757,523	1,690,756
Construction and Land Development [Member] | Total Commercial [Member] | Pass-Watch [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	9,280	12,097
Construction and Land Development [Member] | Total Commercial [Member] | Special Mention [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	890	196
Construction and Land Development [Member] | Total Commercial [Member] | Substandard [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	$ 559	$ 543