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, 2024	Dec. 31, 2023
Financing Receivable, Past Due [Line Items]
Loans	$ 49,922,042	$ 50,210,295
Non-Accrual Loans	287,292	291,871
Non-Accrual Loans Without Allowance for Loan Losses	138,443	115,126
Financial Asset, Past Due
Financing Receivable, Past Due [Line Items]
Loans	361,680	383,497
30-59  Days  Past Due Loans
Financing Receivable, Past Due [Line Items]
Loans	46,844	59,214
60-89  Days  Past Due Loans
Financing Receivable, Past Due [Line Items]
Loans	14,189	19,267
90 Days or More Past Due Loans
Financing Receivable, Past Due [Line Items]
Loans	13,355	13,145
Current Loans
Financing Receivable, Past Due [Line Items]
Loans	49,560,362	49,826,798
Commercial and industrial
Financing Receivable, Past Due [Line Items]
Loans	9,104,193	9,230,543
Non-Accrual Loans	102,399	99,912
Non-Accrual Loans Without Allowance for Loan Losses	12,502	6,594
Commercial and industrial | Financial Asset, Past Due
Financing Receivable, Past Due [Line Items]
Loans	117,016	119,893
Commercial and industrial | 30-59  Days  Past Due Loans
Financing Receivable, Past Due [Line Items]
Loans	6,202	9,307
Commercial and industrial | 60-89  Days  Past Due Loans
Financing Receivable, Past Due [Line Items]
Loans	2,665	5,095
Commercial and industrial | 90 Days or More Past Due Loans
Financing Receivable, Past Due [Line Items]
Loans	5,750	5,579
Commercial and industrial | Current Loans
Financing Receivable, Past Due [Line Items]
Loans	8,987,177	9,110,650
Commercial real estate
Financing Receivable, Past Due [Line Items]
Loans	31,705,464	31,970,047
Non-Accrual Loans	151,894	160,590
Non-Accrual Loans Without Allowance for Loan Losses	101,687	93,289
Commercial real estate | Financial Asset, Past Due
Financing Receivable, Past Due [Line Items]
Loans	165,395	168,845
Commercial real estate | 30-59  Days  Past Due Loans
Financing Receivable, Past Due [Line Items]
Loans	5,791	3,008
Commercial real estate | 60-89  Days  Past Due Loans
Financing Receivable, Past Due [Line Items]
Loans	3,720	1,257
Commercial real estate | 90 Days or More Past Due Loans
Financing Receivable, Past Due [Line Items]
Loans	3,990	3,990
Commercial real estate | Current Loans
Financing Receivable, Past Due [Line Items]
Loans	31,540,069	31,801,202
Commercial real estate | Commercial real estate
Financing Receivable, Past Due [Line Items]
Loans	28,148,953	28,243,239
Non-Accrual Loans	100,052	99,739
Non-Accrual Loans Without Allowance for Loan Losses	76,495	81,282
Commercial real estate | Commercial real estate | Financial Asset, Past Due
Financing Receivable, Past Due [Line Items]
Loans	109,563	104,004
Commercial real estate | Commercial real estate | 30-59  Days  Past Due Loans
Financing Receivable, Past Due [Line Items]
Loans	5,791	3,008
Commercial real estate | Commercial real estate | 60-89  Days  Past Due Loans
Financing Receivable, Past Due [Line Items]
Loans	3,720	1,257
Commercial real estate | Commercial real estate | 90 Days or More Past Due Loans
Financing Receivable, Past Due [Line Items]
Loans	0	0
Commercial real estate | Commercial real estate | Current Loans
Financing Receivable, Past Due [Line Items]
Loans	28,039,390	28,139,235
Commercial real estate | Construction
Financing Receivable, Past Due [Line Items]
Loans	3,556,511	3,726,808
Non-Accrual Loans	51,842	60,851
Non-Accrual Loans Without Allowance for Loan Losses	25,192	12,007
Commercial real estate | Construction | Financial Asset, Past Due
Financing Receivable, Past Due [Line Items]
Loans	55,832	64,841
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	3,500,679	3,661,967
Residential mortgage
Financing Receivable, Past Due [Line Items]
Loans	5,618,355	5,569,010
Non-Accrual Loans	28,561	26,986
Non-Accrual Loans Without Allowance for Loan Losses	23,338	14,654
Residential mortgage | Financial Asset, Past Due
Financing Receivable, Past Due [Line Items]
Loans	58,234	64,019
Residential mortgage | 30-59  Days  Past Due Loans
Financing Receivable, Past Due [Line Items]
Loans	20,819	26,345
Residential mortgage | 60-89  Days  Past Due Loans
Financing Receivable, Past Due [Line Items]
Loans	5,970	8,200
Residential mortgage | 90 Days or More Past Due Loans
Financing Receivable, Past Due [Line Items]
Loans	2,884	2,488
Residential mortgage | Current Loans
Financing Receivable, Past Due [Line Items]
Loans	5,560,121	5,504,991
Consumer loans
Financing Receivable, Past Due [Line Items]
Loans	3,494,030	3,440,695
Non-Accrual Loans	4,438	4,383
Non-Accrual Loans Without Allowance for Loan Losses	916	589
Consumer loans | Financial Asset, Past Due
Financing Receivable, Past Due [Line Items]
Loans	21,035	30,740
Consumer loans | 30-59  Days  Past Due Loans
Financing Receivable, Past Due [Line Items]
Loans	14,032	20,554
Consumer loans | 60-89  Days  Past Due Loans
Financing Receivable, Past Due [Line Items]
Loans	1,834	4,715
Consumer loans | 90 Days or More Past Due Loans
Financing Receivable, Past Due [Line Items]
Loans	731	1,088
Consumer loans | Current Loans
Financing Receivable, Past Due [Line Items]
Loans	3,472,995	3,409,955
Consumer loans | Home equity
Financing Receivable, Past Due [Line Items]
Loans	564,083	559,152
Non-Accrual Loans	3,506	3,539
Non-Accrual Loans Without Allowance for Loan Losses	327	0
Consumer loans | Home equity | Financial Asset, Past Due
Financing Receivable, Past Due [Line Items]
Loans	4,530	5,839
Consumer loans | Home equity | 30-59  Days  Past Due Loans
Financing Receivable, Past Due [Line Items]
Loans	1,006	1,687
Consumer loans | Home equity | 60-89  Days  Past Due Loans
Financing Receivable, Past Due [Line Items]
Loans	18	613
Consumer loans | Home equity | 90 Days or More Past Due Loans
Financing Receivable, Past Due [Line Items]
Loans	0	0
Consumer loans | Home equity | Current Loans
Financing Receivable, Past Due [Line Items]
Loans	559,553	553,313
Consumer loans | Automobile
Financing Receivable, Past Due [Line Items]
Loans	1,700,508	1,620,389
Non-Accrual Loans	305	212
Non-Accrual Loans Without Allowance for Loan Losses	0	0
Consumer loans | Automobile | Financial Asset, Past Due
Financing Receivable, Past Due [Line Items]
Loans	10,677	14,493
Consumer loans | Automobile | 30-59  Days  Past Due Loans
Financing Receivable, Past Due [Line Items]
Loans	8,450	11,850
Consumer loans | Automobile | 60-89  Days  Past Due Loans
Financing Receivable, Past Due [Line Items]
Loans	1,387	1,855
Consumer loans | Automobile | 90 Days or More Past Due Loans
Financing Receivable, Past Due [Line Items]
Loans	535	576
Consumer loans | Automobile | Current Loans
Financing Receivable, Past Due [Line Items]
Loans	1,689,831	1,605,896
Consumer loans | Other consumer
Financing Receivable, Past Due [Line Items]
Loans	1,229,439	1,261,154
Non-Accrual Loans	627	632
Non-Accrual Loans Without Allowance for Loan Losses	589	589
Consumer loans | Other consumer | Financial Asset, Past Due
Financing Receivable, Past Due [Line Items]
Loans	5,828	10,408
Consumer loans | Other consumer | 30-59  Days  Past Due Loans
Financing Receivable, Past Due [Line Items]
Loans	4,576	7,017
Consumer loans | Other consumer | 60-89  Days  Past Due Loans
Financing Receivable, Past Due [Line Items]
Loans	429	2,247
Consumer loans | Other consumer | 90 Days or More Past Due Loans
Financing Receivable, Past Due [Line Items]
Loans	196	512
Consumer loans | Other consumer | Current Loans
Financing Receivable, Past Due [Line Items]
Loans	$ 1,223,611	$ 1,250,746