Loans and Allowance for Credit Losses (Credit Quality Indicators by Segment and Portfolio Class) (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Total Commercial [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	$ 18,591,095	$ 18,589,081
Total Commercial [Member] | Total Commercial And Industrial [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	13,006,525	13,051,047
Total Commercial [Member] | Pass [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	17,780,196	17,881,759
Total Commercial [Member] | Pass [Member] | Total Commercial And Industrial [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	12,396,053	12,540,295
Total Commercial [Member] | Pass-Watch [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	471,028	433,630
Total Commercial [Member] | Pass-Watch [Member] | Total Commercial And Industrial [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	318,753	286,238
Total Commercial [Member] | Special Mention [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	49,439	59,315
Total Commercial [Member] | Special Mention [Member] | Total Commercial And Industrial [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	42,725	18,133
Total Commercial [Member] | Substandard [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	290,432	214,377
Total Commercial [Member] | Substandard [Member] | Total Commercial And Industrial [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	248,994	206,381
Residential Mortgages [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	3,983,321	3,886,072
Residential Mortgages [Member] | Performing [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	3,957,398	3,859,935
Residential Mortgages [Member] | Nonperforming [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	25,923	26,137
Consumer [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	1,396,522	1,446,764
Consumer [Member] | Performing [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	1,386,342	1,438,209
Consumer [Member] | Nonperforming [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	10,180	8,555
Residential Mortgage and Consumer [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	5,379,843	5,332,836
Residential Mortgage and Consumer [Member] | Performing [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	5,343,740	5,298,144
Residential Mortgage and Consumer [Member] | Nonperforming [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	36,103	34,692
Commercial Non-Real Estate [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	9,926,333	9,957,284
Commercial Non-Real Estate [Member] | Pass [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	9,407,861	9,524,018
Commercial Non-Real Estate [Member] | Pass-Watch [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	255,418	234,211
Commercial Non-Real Estate [Member] | Special Mention [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	25,058	11,486
Commercial Non-Real Estate [Member] | Substandard [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	237,996	187,569
Commercial Non-Real Estate [Member] | Total Commercial [Member] | Total Commercial And Industrial [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	9,926,333	9,957,284
Commercial Non-Real Estate [Member] | Total Commercial [Member] | Pass [Member] | Total Commercial And Industrial [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	9,407,861	9,524,018
Commercial Non-Real Estate [Member] | Total Commercial [Member] | Pass-Watch [Member] | Total Commercial And Industrial [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	255,418	234,211
Commercial Non-Real Estate [Member] | Total Commercial [Member] | Special Mention [Member] | Total Commercial And Industrial [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	25,058	11,486
Commercial Non-Real Estate [Member] | Total Commercial [Member] | Substandard [Member] | Total Commercial And Industrial [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	237,996	187,569
Commercial Real Estate - Owner Occupied [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	3,080,192	3,093,763
Commercial Real Estate - Owner Occupied [Member] | Pass [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	2,988,192	3,016,277
Commercial Real Estate - Owner Occupied [Member] | Pass-Watch [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	63,335	52,027
Commercial Real Estate - Owner Occupied [Member] | Special Mention [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	17,667	6,647
Commercial Real Estate - Owner Occupied [Member] | Substandard [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	10,998	18,812
Commercial Real Estate - Owner Occupied [Member] | Total Commercial [Member] | Total Commercial And Industrial [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	3,080,192	3,093,763
Commercial Real Estate - Owner Occupied [Member] | Total Commercial [Member] | Pass [Member] | Total Commercial And Industrial [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	2,988,192	3,016,277
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	63,335	52,027
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	17,667	6,647
Commercial Real Estate - Owner Occupied [Member] | Total Commercial [Member] | Substandard [Member] | Total Commercial And Industrial [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	10,998	18,812
Commercial Real Estate - Income Producing [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	4,042,797	3,986,943
Commercial Real Estate - Income Producing [Member] | Pass [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	3,862,625	3,799,004
Commercial Real Estate - Income Producing [Member] | Pass-Watch [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	134,248	139,932
Commercial Real Estate - Income Producing [Member] | Special Mention [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	6,714	40,826
Commercial Real Estate - Income Producing [Member] | Substandard [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	39,210	7,181
Commercial Real Estate - Income Producing [Member] | Total Commercial [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	4,042,797	3,986,943
Commercial Real Estate - Income Producing [Member] | Total Commercial [Member] | Pass [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	3,862,625	3,799,004
Commercial Real Estate - Income Producing [Member] | Total Commercial [Member] | Pass-Watch [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	134,248	139,932
Commercial Real Estate - Income Producing [Member] | Total Commercial [Member] | Special Mention [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	6,714	40,826
Commercial Real Estate - Income Producing [Member] | Total Commercial [Member] | Substandard [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	39,210	7,181
Construction and Land Development [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	1,541,773	1,551,091
Construction and Land Development [Member] | Pass [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	1,521,518	1,542,460
Construction and Land Development [Member] | Pass-Watch [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	18,027	7,460
Construction and Land Development [Member] | Special Mention [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans		356
Construction and Land Development [Member] | Substandard [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	2,228	815
Construction and Land Development [Member] | Total Commercial [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	1,541,773	1,551,091
Construction and Land Development [Member] | Total Commercial [Member] | Pass [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	1,521,518	1,542,460
Construction and Land Development [Member] | Total Commercial [Member] | Pass-Watch [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	18,027	7,460
Construction and Land Development [Member] | Total Commercial [Member] | Special Mention [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	0	356
Construction and Land Development [Member] | Total Commercial [Member] | Substandard [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	$ 2,228	$ 815