Loans and Allowance for Credit Losses for Loans - Past Due, Non-Accrual and Current Loans by Loan Portfolio Class (Details) - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022
Financing Receivable, Past Due [Line Items]
Loans	$ 49,877,248	$ 46,917,200
Non-Accrual Loans	254,091	269,761
Non-Accrual Loans Without Allowance for Loan Losses	116,286	102,186
Financial Asset, Past Due
Financing Receivable, Past Due [Line Items]
Loans	315,872	360,649
30-59  Days  Past Due Loans
Financing Receivable, Past Due [Line Items]
Loans	33,837	43,535
60-89  Days  Past Due Loans
Financing Receivable, Past Due [Line Items]
Loans	12,942	20,766
90 Days or More Past Due Loans
Financing Receivable, Past Due [Line Items]
Loans	15,002	26,587
Current Loans
Financing Receivable, Past Due [Line Items]
Loans	49,561,376	46,556,551
Commercial and industrial
Financing Receivable, Past Due [Line Items]
Loans	9,287,309	8,804,830
Non-Accrual Loans	84,449	98,881
Non-Accrual Loans Without Allowance for Loan Losses	8,221	5,659
Commercial and industrial | Financial Asset, Past Due
Financing Receivable, Past Due [Line Items]
Loans	104,745	141,642
Commercial and industrial | 30-59  Days  Past Due Loans
Financing Receivable, Past Due [Line Items]
Loans	6,229	11,664
Commercial and industrial | 60-89  Days  Past Due Loans
Financing Receivable, Past Due [Line Items]
Loans	7,468	12,705
Commercial and industrial | 90 Days or More Past Due Loans
Financing Receivable, Past Due [Line Items]
Loans	6,599	18,392
Commercial and industrial | Current Loans
Financing Receivable, Past Due [Line Items]
Loans	9,182,564	8,663,188
Commercial real estate
Financing Receivable, Past Due [Line Items]
Loans	31,608,833	29,432,868
Non-Accrual Loans	145,755	142,546
Non-Accrual Loans Without Allowance for Loan Losses	91,914	82,186
Commercial real estate | Financial Asset, Past Due
Financing Receivable, Past Due [Line Items]
Loans	155,599	158,633
Commercial real estate | 30-59  Days  Past Due Loans
Financing Receivable, Past Due [Line Items]
Loans	3,612	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	6,232	6,282
Commercial real estate | Current Loans
Financing Receivable, Past Due [Line Items]
Loans	31,453,234	29,274,235
Commercial real estate | Commercial real estate
Financing Receivable, Past Due [Line Items]
Loans	27,793,072	25,732,033
Non-Accrual Loans	82,712	68,316
Non-Accrual Loans Without Allowance for Loan Losses	76,438	66,066
Commercial real estate | Commercial real estate | Financial Asset, Past Due
Financing Receivable, Past Due [Line Items]
Loans	88,566	80,413
Commercial real estate | Commercial real estate | 30-59  Days  Past Due Loans
Financing Receivable, Past Due [Line Items]
Loans	3,612	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	2,242	2,292
Commercial real estate | Commercial real estate | Current Loans
Financing Receivable, Past Due [Line Items]
Loans	27,704,506	25,651,620
Commercial real estate | Construction
Financing Receivable, Past Due [Line Items]
Loans	3,815,761	3,700,835
Non-Accrual Loans	63,043	74,230
Non-Accrual Loans Without Allowance for Loan Losses	15,476	16,120
Commercial real estate | Construction | Financial Asset, Past Due
Financing Receivable, Past Due [Line Items]
Loans	67,033	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	3,990	3,990
Commercial real estate | Construction | Current Loans
Financing Receivable, Past Due [Line Items]
Loans	3,748,728	3,622,615
Residential mortgage
Financing Receivable, Past Due [Line Items]
Loans	5,560,356	5,364,550
Non-Accrual Loans	20,819	25,160
Non-Accrual Loans Without Allowance for Loan Losses	16,151	14,224
Residential mortgage | Financial Asset, Past Due
Financing Receivable, Past Due [Line Items]
Loans	38,897	46,487
Residential mortgage | 30-59  Days  Past Due Loans
Financing Receivable, Past Due [Line Items]
Loans	15,565	16,146
Residential mortgage | 60-89  Days  Past Due Loans
Financing Receivable, Past Due [Line Items]
Loans	1,348	3,315
Residential mortgage | 90 Days or More Past Due Loans
Financing Receivable, Past Due [Line Items]
Loans	1,165	1,866
Residential mortgage | Current Loans
Financing Receivable, Past Due [Line Items]
Loans	5,521,459	5,318,063
Consumer
Financing Receivable, Past Due [Line Items]
Loans	3,420,750	3,314,952
Non-Accrual Loans	3,068	3,174
Non-Accrual Loans Without Allowance for Loan Losses	0	117
Consumer | Financial Asset, Past Due
Financing Receivable, Past Due [Line Items]
Loans	16,631	13,887
Consumer | 30-59  Days  Past Due Loans
Financing Receivable, Past Due [Line Items]
Loans	8,431	9,087
Consumer | 60-89  Days  Past Due Loans
Financing Receivable, Past Due [Line Items]
Loans	4,126	1,579
Consumer | 90 Days or More Past Due Loans
Financing Receivable, Past Due [Line Items]
Loans	1,006	47
Consumer | Current Loans
Financing Receivable, Past Due [Line Items]
Loans	3,404,119	3,301,065
Consumer | Home equity
Financing Receivable, Past Due [Line Items]
Loans	535,493	503,884
Non-Accrual Loans	2,737	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	3,742	4,019
Consumer | Home equity | 30-59  Days  Past Due Loans
Financing Receivable, Past Due [Line Items]
Loans	959	955
Consumer | Home equity | 60-89  Days  Past Due Loans
Financing Receivable, Past Due [Line Items]
Loans	46	254
Consumer | Home equity | 90 Days or More Past Due Loans
Financing Receivable, Past Due [Line Items]
Loans	0	0
Consumer | Home equity | Current Loans
Financing Receivable, Past Due [Line Items]
Loans	531,751	499,865
Consumer | Automobile
Financing Receivable, Past Due [Line Items]
Loans	1,632,875	1,746,225
Non-Accrual Loans	248	271
Non-Accrual Loans Without Allowance for Loan Losses	0	0
Consumer | Automobile | Financial Asset, Past Due
Financing Receivable, Past Due [Line Items]
Loans	7,111	6,876
Consumer | Automobile | 30-59  Days  Past Due Loans
Financing Receivable, Past Due [Line Items]
Loans	5,963	5,974
Consumer | Automobile | 60-89  Days  Past Due Loans
Financing Receivable, Past Due [Line Items]
Loans	568	630
Consumer | Automobile | 90 Days or More Past Due Loans
Financing Receivable, Past Due [Line Items]
Loans	332	1
Consumer | Automobile | Current Loans
Financing Receivable, Past Due [Line Items]
Loans	1,625,764	1,739,349
Consumer | Other consumer
Financing Receivable, Past Due [Line Items]
Loans	1,252,382	1,064,843
Non-Accrual Loans	83	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	5,778	2,992
Consumer | Other consumer | 30-59  Days  Past Due Loans
Financing Receivable, Past Due [Line Items]
Loans	1,509	2,158
Consumer | Other consumer | 60-89  Days  Past Due Loans
Financing Receivable, Past Due [Line Items]
Loans	3,512	695
Consumer | Other consumer | 90 Days or More Past Due Loans
Financing Receivable, Past Due [Line Items]
Loans	674	46
Consumer | Other consumer | Current Loans
Financing Receivable, Past Due [Line Items]
Loans	$ 1,246,604	$ 1,061,851