Loans and Allowance for Credit Losses for Loans - Past Due, Non-Accrual and Current Loans by Loan Portfolio Class (Details) - USD ($) $ in Thousands	Mar. 31, 2023	Dec. 31, 2022
Financing Receivable, Past Due [Line Items]
Loans	$ 48,659,966	$ 46,917,200
Non-Accrual Loans	241,994	269,761
Non-Accrual Loans Without Allowance for Loan Losses	107,747	102,186
Financial Asset, Past Due
Financing Receivable, Past Due [Line Items]
Loans	342,296	360,649
30-59  Days  Past Due Loans
Financing Receivable, Past Due [Line Items]
Loans	54,740	43,535
60-89  Days  Past Due Loans
Financing Receivable, Past Due [Line Items]
Loans	27,770	20,766
90 Days or More Past Due Loans
Financing Receivable, Past Due [Line Items]
Loans	17,792	26,587
Current Loans
Financing Receivable, Past Due [Line Items]
Loans	48,317,670	46,556,551
Commercial and industrial
Financing Receivable, Past Due [Line Items]
Loans	9,043,946	8,804,830
Non-Accrual Loans	78,606	98,881
Non-Accrual Loans Without Allowance for Loan Losses	6,675	5,659
Commercial and industrial | Financial Asset, Past Due
Financing Receivable, Past Due [Line Items]
Loans	132,367	141,642
Commercial and industrial | 30-59  Days  Past Due Loans
Financing Receivable, Past Due [Line Items]
Loans	20,716	11,664
Commercial and industrial | 60-89  Days  Past Due Loans
Financing Receivable, Past Due [Line Items]
Loans	24,118	12,705
Commercial and industrial | 90 Days or More Past Due Loans
Financing Receivable, Past Due [Line Items]
Loans	8,927	18,392
Commercial and industrial | Current Loans
Financing Receivable, Past Due [Line Items]
Loans	8,911,579	8,663,188
Commercial real estate
Financing Receivable, Past Due [Line Items]
Loans	30,777,078	29,432,868
Non-Accrual Loans	136,587	142,546
Non-Accrual Loans Without Allowance for Loan Losses	82,378	82,186
Commercial real estate | Financial Asset, Past Due
Financing Receivable, Past Due [Line Items]
Loans	156,617	158,633
Commercial real estate | 30-59  Days  Past Due Loans
Financing Receivable, Past Due [Line Items]
Loans	13,580	6,638
Commercial real estate | 60-89  Days  Past Due Loans
Financing Receivable, Past Due [Line Items]
Loans	0	3,167
Commercial real estate | 90 Days or More Past Due Loans
Financing Receivable, Past Due [Line Items]
Loans	6,450	6,282
Commercial real estate | Current Loans
Financing Receivable, Past Due [Line Items]
Loans	30,620,461	29,274,235
Commercial real estate | Commercial real estate
Financing Receivable, Past Due [Line Items]
Loans	27,051,111	25,732,033
Non-Accrual Loans	67,938	68,316
Non-Accrual Loans Without Allowance for Loan Losses	66,587	66,066
Commercial real estate | Commercial real estate | Financial Asset, Past Due
Financing Receivable, Past Due [Line Items]
Loans	81,518	80,413
Commercial real estate | Commercial real estate | 30-59  Days  Past Due Loans
Financing Receivable, Past Due [Line Items]
Loans	13,580	6,638
Commercial real estate | Commercial real estate | 60-89  Days  Past Due Loans
Financing Receivable, Past Due [Line Items]
Loans	0	3,167
Commercial real estate | Commercial real estate | 90 Days or More Past Due Loans
Financing Receivable, Past Due [Line Items]
Loans	0	2,292
Commercial real estate | Commercial real estate | Current Loans
Financing Receivable, Past Due [Line Items]
Loans	26,969,593	25,651,620
Commercial real estate | Construction
Financing Receivable, Past Due [Line Items]
Loans	3,725,967	3,700,835
Non-Accrual Loans	68,649	74,230
Non-Accrual Loans Without Allowance for Loan Losses	15,791	16,120
Commercial real estate | Construction | Financial Asset, Past Due
Financing Receivable, Past Due [Line Items]
Loans	75,099	78,220
Commercial real estate | Construction | 30-59  Days  Past Due Loans
Financing Receivable, Past Due [Line Items]
Loans	0	0
Commercial real estate | Construction | 60-89  Days  Past Due Loans
Financing Receivable, Past Due [Line Items]
Loans	0	0
Commercial real estate | Construction | 90 Days or More Past Due Loans
Financing Receivable, Past Due [Line Items]
Loans	6,450	3,990
Commercial real estate | Construction | Current Loans
Financing Receivable, Past Due [Line Items]
Loans	3,650,868	3,622,615
Residential mortgage
Financing Receivable, Past Due [Line Items]
Loans	5,486,280	5,364,550
Non-Accrual Loans	23,483	25,160
Non-Accrual Loans Without Allowance for Loan Losses	18,694	14,224
Residential mortgage | Financial Asset, Past Due
Financing Receivable, Past Due [Line Items]
Loans	39,883	46,487
Residential mortgage | 30-59  Days  Past Due Loans
Financing Receivable, Past Due [Line Items]
Loans	12,599	16,146
Residential mortgage | 60-89  Days  Past Due Loans
Financing Receivable, Past Due [Line Items]
Loans	2,133	3,315
Residential mortgage | 90 Days or More Past Due Loans
Financing Receivable, Past Due [Line Items]
Loans	1,668	1,866
Residential mortgage | Current Loans
Financing Receivable, Past Due [Line Items]
Loans	5,446,397	5,318,063
Consumer
Financing Receivable, Past Due [Line Items]
Loans	3,352,662	3,314,952
Non-Accrual Loans	3,318	3,174
Non-Accrual Loans Without Allowance for Loan Losses	0	117
Consumer | Financial Asset, Past Due
Financing Receivable, Past Due [Line Items]
Loans	13,429	13,887
Consumer | 30-59  Days  Past Due Loans
Financing Receivable, Past Due [Line Items]
Loans	7,845	9,087
Consumer | 60-89  Days  Past Due Loans
Financing Receivable, Past Due [Line Items]
Loans	1,519	1,579
Consumer | 90 Days or More Past Due Loans
Financing Receivable, Past Due [Line Items]
Loans	747	47
Consumer | Current Loans
Financing Receivable, Past Due [Line Items]
Loans	3,339,233	3,301,065
Consumer | Home equity
Financing Receivable, Past Due [Line Items]
Loans	516,592	503,884
Non-Accrual Loans	2,965	2,810
Non-Accrual Loans Without Allowance for Loan Losses	0	117
Consumer | Home equity | Financial Asset, Past Due
Financing Receivable, Past Due [Line Items]
Loans	3,712	4,019
Consumer | Home equity | 30-59  Days  Past Due Loans
Financing Receivable, Past Due [Line Items]
Loans	412	955
Consumer | Home equity | 60-89  Days  Past Due Loans
Financing Receivable, Past Due [Line Items]
Loans	287	254
Consumer | Home equity | 90 Days or More Past Due Loans
Financing Receivable, Past Due [Line Items]
Loans	48	0
Consumer | Home equity | Current Loans
Financing Receivable, Past Due [Line Items]
Loans	512,880	499,865
Consumer | Automobile
Financing Receivable, Past Due [Line Items]
Loans	1,717,141	1,746,225
Non-Accrual Loans	262	271
Non-Accrual Loans Without Allowance for Loan Losses	0	0
Consumer | Automobile | Financial Asset, Past Due
Financing Receivable, Past Due [Line Items]
Loans	5,644	6,876
Consumer | Automobile | 30-59  Days  Past Due Loans
Financing Receivable, Past Due [Line Items]
Loans	4,598	5,974
Consumer | Automobile | 60-89  Days  Past Due Loans
Financing Receivable, Past Due [Line Items]
Loans	502	630
Consumer | Automobile | 90 Days or More Past Due Loans
Financing Receivable, Past Due [Line Items]
Loans	282	1
Consumer | Automobile | Current Loans
Financing Receivable, Past Due [Line Items]
Loans	1,711,497	1,739,349
Consumer | Other consumer
Financing Receivable, Past Due [Line Items]
Loans	1,118,929	1,064,843
Non-Accrual Loans	91	93
Non-Accrual Loans Without Allowance for Loan Losses	0	0
Consumer | Other consumer | Financial Asset, Past Due
Financing Receivable, Past Due [Line Items]
Loans	4,073	2,992
Consumer | Other consumer | 30-59  Days  Past Due Loans
Financing Receivable, Past Due [Line Items]
Loans	2,835	2,158
Consumer | Other consumer | 60-89  Days  Past Due Loans
Financing Receivable, Past Due [Line Items]
Loans	730	695
Consumer | Other consumer | 90 Days or More Past Due Loans
Financing Receivable, Past Due [Line Items]
Loans	417	46
Consumer | Other consumer | Current Loans
Financing Receivable, Past Due [Line Items]
Loans	$ 1,114,856	$ 1,061,851