Loans and Allowance for Credit Losses (Credit Quality Indicators by Segment and Portfolio Class) (Details) - USD ($) $ in Thousands	Mar. 31, 2025	Dec. 31, 2024
Total Commercial [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	$ 17,735,175	$ 17,968,274
Total Commercial [Member] | Total Commercial And Industrial [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	12,637,592	12,888,547
Total Commercial [Member] | Pass [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	16,637,397	16,823,845
Total Commercial [Member] | Pass [Member] | Total Commercial And Industrial [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	11,757,864	11,990,460
Total Commercial [Member] | Pass-Watch [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	503,694	521,400
Total Commercial [Member] | Pass-Watch [Member] | Total Commercial And Industrial [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	362,307	355,541
Total Commercial [Member] | Special Mention [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	227,576	190,898
Total Commercial [Member] | Special Mention [Member] | Total Commercial And Industrial [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	206,257	167,606
Total Commercial [Member] | Substandard [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	366,508	432,131
Total Commercial [Member] | Substandard [Member] | Total Commercial And Industrial [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	311,164	374,940
Residential Mortgages [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	4,025,145	3,961,328
Residential Mortgages [Member] | Performing [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	3,978,741	3,917,242
Residential Mortgages [Member] | Nonperforming [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	46,404	44,086
Consumer [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	1,337,826	1,369,845
Consumer [Member] | Performing [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	1,326,768	1,358,658
Consumer [Member] | Nonperforming [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	11,058	11,187
Residential Mortgage and Consumer [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	5,362,971	5,331,173
Residential Mortgage and Consumer [Member] | Performing [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	5,305,509	5,275,900
Residential Mortgage and Consumer [Member] | Nonperforming [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	57,462	55,273
Commercial Non-Real Estate [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	9,636,594	9,876,592
Commercial Non-Real Estate [Member] | Pass [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	8,945,725	9,157,232
Commercial Non-Real Estate [Member] | Pass-Watch [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	216,495	219,975
Commercial Non-Real Estate [Member] | Special Mention [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	189,227	149,705
Commercial Non-Real Estate [Member] | Substandard [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	285,147	349,680
Commercial Non-Real Estate [Member] | Total Commercial [Member] | Total Commercial And Industrial [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	9,636,594	9,876,592
Commercial Non-Real Estate [Member] | Total Commercial [Member] | Pass [Member] | Total Commercial And Industrial [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	8,945,725	9,157,232
Commercial Non-Real Estate [Member] | Total Commercial [Member] | Pass-Watch [Member] | Total Commercial And Industrial [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	216,495	219,975
Commercial Non-Real Estate [Member] | Total Commercial [Member] | Special Mention [Member] | Total Commercial And Industrial [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	189,227	149,705
Commercial Non-Real Estate [Member] | Total Commercial [Member] | Substandard [Member] | Total Commercial And Industrial [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	285,147	349,680
Commercial Real Estate - Owner Occupied [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	3,000,998	3,011,955
Commercial Real Estate - Owner Occupied [Member] | Pass [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	2,812,139	2,833,228
Commercial Real Estate - Owner Occupied [Member] | Pass-Watch [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	145,812	135,566
Commercial Real Estate - Owner Occupied [Member] | Special Mention [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	17,030	17,901
Commercial Real Estate - Owner Occupied [Member] | Substandard [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	26,017	25,260
Commercial Real Estate - Owner Occupied [Member] | Total Commercial [Member] | Total Commercial And Industrial [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	3,000,998	3,011,955
Commercial Real Estate - Owner Occupied [Member] | Total Commercial [Member] | Pass [Member] | Total Commercial And Industrial [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	2,812,139	2,833,228
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	145,812	135,566
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	17,030	17,901
Commercial Real Estate - Owner Occupied [Member] | Total Commercial [Member] | Substandard [Member] | Total Commercial And Industrial [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	26,017	25,260
Commercial Real Estate - Income Producing [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	3,809,664	3,798,612
Commercial Real Estate - Income Producing [Member] | Pass [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	3,662,669	3,625,981
Commercial Real Estate - Income Producing [Member] | Pass-Watch [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	73,241	99,638
Commercial Real Estate - Income Producing [Member] | Special Mention [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	21,126	22,278
Commercial Real Estate - Income Producing [Member] | Substandard [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	52,628	50,715
Commercial Real Estate - Income Producing [Member] | Total Commercial [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	3,809,664	3,798,612
Commercial Real Estate - Income Producing [Member] | Total Commercial [Member] | Pass [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	3,662,669	3,625,981
Commercial Real Estate - Income Producing [Member] | Total Commercial [Member] | Pass-Watch [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	73,241	99,638
Commercial Real Estate - Income Producing [Member] | Total Commercial [Member] | Special Mention [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	21,126	22,278
Commercial Real Estate - Income Producing [Member] | Total Commercial [Member] | Substandard [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	52,628	50,715
Construction and Land Development [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	1,287,919	1,281,115
Construction and Land Development [Member] | Pass [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	1,216,864	1,207,404
Construction and Land Development [Member] | Pass-Watch [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	68,146	66,221
Construction and Land Development [Member] | Special Mention [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	193	1,014
Construction and Land Development [Member] | Substandard [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	2,716	6,476
Construction and Land Development [Member] | Total Commercial [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	1,287,919	1,281,115
Construction and Land Development [Member] | Total Commercial [Member] | Pass [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	1,216,864	1,207,404
Construction and Land Development [Member] | Total Commercial [Member] | Pass-Watch [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	68,146	66,221
Construction and Land Development [Member] | Total Commercial [Member] | Special Mention [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	193	1,014
Construction and Land Development [Member] | Total Commercial [Member] | Substandard [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	$ 2,716	$ 6,476