Loans and Allowance for Credit Losses for Loans - Past Due, Current, and Non-Accrual Loans Without an Allowance for Credit Losses by Loan Portfolio Class (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Financing Receivable, Past Due [Line Items]
Loans	$ 34,153,657	$ 32,217,112
Non-Accrual Loans	240,216	185,282
Non-Accrual Loans Without Allowance for Loan Losses	100,190	48,151
Financial Asset, Past Due
Financing Receivable, Past Due [Line Items]
Loans	296,080	284,287
30-59 Days Past Due Loans
Financing Receivable, Past Due [Line Items]
Loans	40,889	69,712
60-89 Days Past Due Loans
Financing Receivable, Past Due [Line Items]
Loans	12,204	15,752
90 Days or More Past Due Loans
Financing Receivable, Past Due [Line Items]
Loans	2,771	13,541
Current Loans
Financing Receivable, Past Due [Line Items]
Loans	33,857,577	31,932,825
Commercial and industrial
Financing Receivable, Past Due [Line Items]
Loans	5,847,551	6,861,708
Non-Accrual Loans	99,918	106,693
Non-Accrual Loans Without Allowance for Loan Losses	9,066	4,075
Commercial and industrial | Financial Asset, Past Due
Financing Receivable, Past Due [Line Items]
Loans	115,778	124,445
Commercial and industrial | 30-59 Days Past Due Loans
Financing Receivable, Past Due [Line Items]
Loans	6,717	6,393
Commercial and industrial | 60-89 Days Past Due Loans
Financing Receivable, Past Due [Line Items]
Loans	7,870	2,252
Commercial and industrial | 90 Days or More Past Due Loans
Financing Receivable, Past Due [Line Items]
Loans	1,273	9,107
Commercial and industrial | Current Loans
Financing Receivable, Past Due [Line Items]
Loans	5,731,773	6,737,263
Commercial real estate
Financing Receivable, Past Due [Line Items]
Loans	20,790,066	18,470,823
Non-Accrual Loans	101,233	46,963
Non-Accrual Loans Without Allowance for Loan Losses	70,719	32,416
Commercial real estate | Financial Asset, Past Due
Financing Receivable, Past Due [Line Items]
Loans	117,627	84,627
Commercial real estate | 30-59 Days Past Due Loans
Financing Receivable, Past Due [Line Items]
Loans	16,362	35,345
Commercial real estate | 60-89 Days Past Due Loans
Financing Receivable, Past Due [Line Items]
Loans	0	1,326
Commercial real estate | 90 Days or More Past Due Loans
Financing Receivable, Past Due [Line Items]
Loans	32	993
Commercial real estate | Current Loans
Financing Receivable, Past Due [Line Items]
Loans	20,672,439	18,386,196
Commercial real estate | Commercial real estate
Financing Receivable, Past Due [Line Items]
Loans	18,935,486	16,724,998
Non-Accrual Loans	83,592	46,879
Non-Accrual Loans Without Allowance for Loan Losses	70,719	32,416
Commercial real estate | Commercial real estate | Financial Asset, Past Due
Financing Receivable, Past Due [Line Items]
Loans	98,045	84,228
Commercial real estate | Commercial real estate | 30-59 Days Past Due Loans
Financing Receivable, Past Due [Line Items]
Loans	14,421	35,030
Commercial real estate | Commercial real estate | 60-89 Days Past Due Loans
Financing Receivable, Past Due [Line Items]
Loans	0	1,326
Commercial real estate | Commercial real estate | 90 Days or More Past Due Loans
Financing Receivable, Past Due [Line Items]
Loans	32	993
Commercial real estate | Commercial real estate | Current Loans
Financing Receivable, Past Due [Line Items]
Loans	18,837,441	16,640,770
Commercial real estate | Construction
Financing Receivable, Past Due [Line Items]
Loans	1,854,580	1,745,825
Non-Accrual Loans	17,641	84
Non-Accrual Loans Without Allowance for Loan Losses	0	0
Commercial real estate | Construction | Financial Asset, Past Due
Financing Receivable, Past Due [Line Items]
Loans	19,582	399
Commercial real estate | Construction | 30-59 Days Past Due Loans
Financing Receivable, Past Due [Line Items]
Loans	1,941	315
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	0	0
Commercial real estate | Construction | Current Loans
Financing Receivable, Past Due [Line Items]
Loans	1,834,998	1,745,426
Residential mortgage
Financing Receivable, Past Due [Line Items]
Loans	4,545,064	4,183,743
Non-Accrual Loans	35,207	25,817
Non-Accrual Loans Without Allowance for Loan Losses	20,401	11,610
Residential mortgage | Financial Asset, Past Due
Financing Receivable, Past Due [Line Items]
Loans	50,197	57,055
Residential mortgage | 30-59 Days Past Due Loans
Financing Receivable, Past Due [Line Items]
Loans	10,999	17,717
Residential mortgage | 60-89 Days Past Due Loans
Financing Receivable, Past Due [Line Items]
Loans	3,314	10,351
Residential mortgage | 90 Days or More Past Due Loans
Financing Receivable, Past Due [Line Items]
Loans	677	3,170
Residential mortgage | Current Loans
Financing Receivable, Past Due [Line Items]
Loans	4,494,867	4,126,688
Consumer
Financing Receivable, Past Due [Line Items]
Loans	2,970,976	2,700,838
Non-Accrual Loans	3,858	5,809
Non-Accrual Loans Without Allowance for Loan Losses	4	50
Consumer | Financial Asset, Past Due
Financing Receivable, Past Due [Line Items]
Loans	12,478	18,160
Consumer | 30-59 Days Past Due Loans
Financing Receivable, Past Due [Line Items]
Loans	6,811	10,257
Consumer | 60-89 Days Past Due Loans
Financing Receivable, Past Due [Line Items]
Loans	1,020	1,823
Consumer | 90 Days or More Past Due Loans
Financing Receivable, Past Due [Line Items]
Loans	789	271
Consumer | Current Loans
Financing Receivable, Past Due [Line Items]
Loans	2,958,498	2,682,678
Consumer | Home equity
Financing Receivable, Past Due [Line Items]
Loans	400,779	431,553
Non-Accrual Loans	3,517	4,936
Non-Accrual Loans Without Allowance for Loan Losses	4	50
Consumer | Home equity | Financial Asset, Past Due
Financing Receivable, Past Due [Line Items]
Loans	3,857	6,381
Consumer | Home equity | 30-59 Days Past Due Loans
Financing Receivable, Past Due [Line Items]
Loans	242	953
Consumer | Home equity | 60-89 Days Past Due Loans
Financing Receivable, Past Due [Line Items]
Loans	98	492
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	396,922	425,172
Consumer | Automobile
Financing Receivable, Past Due [Line Items]
Loans	1,570,036	1,355,955
Non-Accrual Loans	240	338
Non-Accrual Loans Without Allowance for Loan Losses	0	0
Consumer | Automobile | Financial Asset, Past Due
Financing Receivable, Past Due [Line Items]
Loans	7,558	9,746
Consumer | Automobile | 30-59 Days Past Due Loans
Financing Receivable, Past Due [Line Items]
Loans	6,391	8,056
Consumer | Automobile | 60-89 Days Past Due Loans
Financing Receivable, Past Due [Line Items]
Loans	656	1,107
Consumer | Automobile | 90 Days or More Past Due Loans
Financing Receivable, Past Due [Line Items]
Loans	271	245
Consumer | Automobile | Current Loans
Financing Receivable, Past Due [Line Items]
Loans	1,562,478	1,346,209
Consumer | Other consumer
Financing Receivable, Past Due [Line Items]
Loans	1,000,161	913,330
Non-Accrual Loans	101	535
Non-Accrual Loans Without Allowance for Loan Losses	0	0
Consumer | Other consumer | Financial Asset, Past Due
Financing Receivable, Past Due [Line Items]
Loans	1,063	2,033
Consumer | Other consumer | 30-59 Days Past Due Loans
Financing Receivable, Past Due [Line Items]
Loans	178	1,248
Consumer | Other consumer | 60-89 Days Past Due Loans
Financing Receivable, Past Due [Line Items]
Loans	266	224
Consumer | Other consumer | 90 Days or More Past Due Loans
Financing Receivable, Past Due [Line Items]
Loans	518	26
Consumer | Other consumer | Current Loans
Financing Receivable, Past Due [Line Items]
Loans	$ 999,098	$ 911,297