Allowance for Credit Losses and Credit Quality - Schedule of Amortized Cost Basis of Loans and Leases by Year of Origination (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Financing Receivable, Credit Quality Indicator [Line Items]
2020	$ 5,970,957
2019	6,969,076
2018	4,796,357
2017	3,442,038
2016	2,162,133
2015 and Prior	4,368,123
Financing Receivable, Revolving, Converted to Term Loan	6,398,663
Revolving Loans and Leases Converted to Term Loans and Leases	236,344
Total	34,343,691	$ 34,497,464
Impaired Loans With No Valuation Allowance
Financing Receivable, Credit Quality Indicator [Line Items]
2020	6,742
2019	53,647
2018	62,354
2017	39,538
2016	28,588
2015 and Prior	122,028
Financing Receivable, Revolving, Converted to Term Loan	61,257
Revolving Loans and Leases Converted to Term Loans and Leases	2,567
Total	376,721
Commercial
Financing Receivable, Credit Quality Indicator [Line Items]
2020	4,721,446
2019	5,255,024
2018	3,781,433
2017	2,676,637
2016	1,487,061
2015 and Prior	2,311,344
Financing Receivable, Revolving, Converted to Term Loan	3,449,977
Revolving Loans and Leases Converted to Term Loans and Leases	226,331
Total	23,909,253
Commercial | Impaired Loans With Valuation Allowance
Financing Receivable, Credit Quality Indicator [Line Items]
2020	281
2019	992
2018	697
2017	1,312
2016	482
2015 and Prior	2,744
Financing Receivable, Revolving, Converted to Term Loan	401
Revolving Loans and Leases Converted to Term Loans and Leases	0
Total	6,909
Commercial | Impaired Loans With No Valuation Allowance
Financing Receivable, Credit Quality Indicator [Line Items]
2020	5,549
2019	48,985
2018	58,338
2017	36,800
2016	25,737
2015 and Prior	58,095
Financing Receivable, Revolving, Converted to Term Loan	17,729
Revolving Loans and Leases Converted to Term Loans and Leases	1,534
Total	252,767
Commercial | Commercial and industrial
Financing Receivable, Credit Quality Indicator [Line Items]
2020	3,063,523
2019	2,177,140
2018	1,288,775
2017	731,566
2016	446,207
2015 and Prior	390,992
Financing Receivable, Revolving, Converted to Term Loan	3,413,759
Revolving Loans and Leases Converted to Term Loans and Leases	45,275
Total	11,557,237
Commercial | Commercial and industrial | Impaired Loans With Valuation Allowance
Financing Receivable, Credit Quality Indicator [Line Items]
2020	142
2019	86
2018	0
2017	4
2016	0
2015 and Prior	2,468
Financing Receivable, Revolving, Converted to Term Loan	401
Revolving Loans and Leases Converted to Term Loans and Leases	0
Total	3,101
Commercial | Commercial and industrial | Impaired Loans With No Valuation Allowance
Financing Receivable, Credit Quality Indicator [Line Items]
2020	3,739
2019	38,211
2018	34,112
2017	17,978
2016	12,395
2015 and Prior	16,424
Financing Receivable, Revolving, Converted to Term Loan	17,629
Revolving Loans and Leases Converted to Term Loans and Leases	4
Total	140,492
Commercial | Commercial real estate
Financing Receivable, Credit Quality Indicator [Line Items]
2020	931,659
2019	2,257,760
2018	2,023,169
2017	1,659,468
2016	889,786
2015 and Prior	1,865,488
Financing Receivable, Revolving, Converted to Term Loan	0
Revolving Loans and Leases Converted to Term Loans and Leases	0
Total	9,627,330
Commercial | Commercial real estate | Impaired Loans With Valuation Allowance
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0
2019	0
2018	0
2017	0
2016	0
2015 and Prior	244
Financing Receivable, Revolving, Converted to Term Loan	0
Revolving Loans and Leases Converted to Term Loans and Leases	0
Total	244
Commercial | Commercial real estate | Impaired Loans With No Valuation Allowance
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0
2019	1,079
2018	11,937
2017	11,618
2016	8,810
2015 and Prior	36,808
Financing Receivable, Revolving, Converted to Term Loan	0
Revolving Loans and Leases Converted to Term Loans and Leases	0
Total	70,252
Commercial | Lease financing
Financing Receivable, Credit Quality Indicator [Line Items]
2020	726,264
2019	820,124
2018	469,489
2017	285,603
2016	151,068
2015 and Prior	54,864
Financing Receivable, Revolving, Converted to Term Loan	36,218
Revolving Loans and Leases Converted to Term Loans and Leases	181,056
Total	2,724,686
Commercial | Lease financing | Impaired Loans With Valuation Allowance
Financing Receivable, Credit Quality Indicator [Line Items]
2020	139
2019	906
2018	697
2017	1,308
2016	482
2015 and Prior	32
Financing Receivable, Revolving, Converted to Term Loan	0
Revolving Loans and Leases Converted to Term Loans and Leases	0
Total	3,564
Commercial | Lease financing | Impaired Loans With No Valuation Allowance
Financing Receivable, Credit Quality Indicator [Line Items]
2020	1,810
2019	9,695
2018	12,289
2017	7,204
2016	4,532
2015 and Prior	4,863
Financing Receivable, Revolving, Converted to Term Loan	100
Revolving Loans and Leases Converted to Term Loans and Leases	1,530
Total	42,023
Consumer
Financing Receivable, Credit Quality Indicator [Line Items]
2020	1,249,511
2019	1,714,052
2018	1,014,924
2017	765,401
2016	675,072
2015 and Prior	2,056,779
Financing Receivable, Revolving, Converted to Term Loan	2,948,686
Revolving Loans and Leases Converted to Term Loans and Leases	10,013
Total	10,434,438
Consumer | Impaired Loans With Valuation Allowance
Financing Receivable, Credit Quality Indicator [Line Items]
2020	85
2019	134
2018	0
2017	0
2016	0
2015 and Prior	1,128
Financing Receivable, Revolving, Converted to Term Loan	0
Revolving Loans and Leases Converted to Term Loans and Leases	0
Total	1,347
Consumer | Impaired Loans With No Valuation Allowance
Financing Receivable, Credit Quality Indicator [Line Items]
2020	1,193
2019	4,662
2018	4,016
2017	2,738
2016	2,851
2015 and Prior	63,933
Financing Receivable, Revolving, Converted to Term Loan	43,528
Revolving Loans and Leases Converted to Term Loans and Leases	1,033
Total	123,954
Consumer | Residential mortgage
Financing Receivable, Credit Quality Indicator [Line Items]
2020	1,025,329
2019	1,246,417
2018	747,336
2017	509,612
2016	500,338
2015 and Prior	1,761,219
Financing Receivable, Revolving, Converted to Term Loan	0
Revolving Loans and Leases Converted to Term Loans and Leases	0
Total	5,790,251
Consumer | Residential mortgage | Impaired Loans With Valuation Allowance
Financing Receivable, Credit Quality Indicator [Line Items]
2020	85
2019	134
2018	0
2017	0
2016	0
2015 and Prior	1,128
Financing Receivable, Revolving, Converted to Term Loan	0
Revolving Loans and Leases Converted to Term Loans and Leases	0
Total	1,347
Consumer | Residential mortgage | Impaired Loans With No Valuation Allowance
Financing Receivable, Credit Quality Indicator [Line Items]
2020	476
2019	2,895
2018	2,902
2017	2,112
2016	2,392
2015 and Prior	54,458
Financing Receivable, Revolving, Converted to Term Loan	0
Revolving Loans and Leases Converted to Term Loans and Leases	0
Total	65,235
Consumer | Home equity
Financing Receivable, Credit Quality Indicator [Line Items]
2020	25,194
2019	58,482
2018	54,936
2017	45,243
2016	33,155
2015 and Prior	153,831
Financing Receivable, Revolving, Converted to Term Loan	2,922,199
Revolving Loans and Leases Converted to Term Loans and Leases	9,943
Total	3,302,983
Consumer | Home equity | Impaired Loans With No Valuation Allowance
Financing Receivable, Credit Quality Indicator [Line Items]
2020	675
2019	1,604
2018	458
2017	341
2016	211
2015 and Prior	4,502
Financing Receivable, Revolving, Converted to Term Loan	43,360
Revolving Loans and Leases Converted to Term Loans and Leases	1,033
Total	52,184
Consumer | Consumer installment
Financing Receivable, Credit Quality Indicator [Line Items]
2020	198,988
2019	409,153
2018	212,652
2017	210,546
2016	141,579
2015 and Prior	141,729
Financing Receivable, Revolving, Converted to Term Loan	26,487
Revolving Loans and Leases Converted to Term Loans and Leases	70
Total	1,341,204
Consumer | Consumer installment | Impaired Loans With No Valuation Allowance
Financing Receivable, Credit Quality Indicator [Line Items]
2020	42
2019	163
2018	656
2017	285
2016	248
2015 and Prior	4,973
Financing Receivable, Revolving, Converted to Term Loan	168
Revolving Loans and Leases Converted to Term Loans and Leases	0
Total	6,535
Pass | Commercial | Commercial and industrial
Financing Receivable, Credit Quality Indicator [Line Items]
2020	3,046,289
2019	2,070,267
2018	1,165,510
2017	650,511
2016	412,527
2015 and Prior	354,391
Financing Receivable, Revolving, Converted to Term Loan	3,173,255
Revolving Loans and Leases Converted to Term Loans and Leases	45,162
Total	10,917,912
Pass | Commercial | Commercial real estate
Financing Receivable, Credit Quality Indicator [Line Items]
2020	930,314
2019	2,152,099
2018	1,932,737
2017	1,371,335
2016	784,174
2015 and Prior	1,672,418
Financing Receivable, Revolving, Converted to Term Loan	0
Revolving Loans and Leases Converted to Term Loans and Leases	0
Total	8,843,077
Pass | Commercial | Lease financing
Financing Receivable, Credit Quality Indicator [Line Items]
2020	718,133
2019	797,020
2018	449,720
2017	270,567
2016	143,098
2015 and Prior	47,280
Financing Receivable, Revolving, Converted to Term Loan	31,963
Revolving Loans and Leases Converted to Term Loans and Leases	172,653
Total	2,630,434
Pass | Consumer | Residential mortgage
Financing Receivable, Credit Quality Indicator [Line Items]
2020	1,024,652
2019	1,243,341
2018	743,949
2017	507,124
2016	497,004
2015 and Prior	1,702,326
Financing Receivable, Revolving, Converted to Term Loan	0
Revolving Loans and Leases Converted to Term Loans and Leases	0
Total	5,718,396
Pass | Consumer | Home equity
Financing Receivable, Credit Quality Indicator [Line Items]
2020	24,496
2019	56,729
2018	54,356
2017	44,760
2016	32,586
2015 and Prior	146,650
Financing Receivable, Revolving, Converted to Term Loan	2,871,820
Revolving Loans and Leases Converted to Term Loans and Leases	8,501
Total	3,239,898
Pass | Consumer | Consumer installment
Financing Receivable, Credit Quality Indicator [Line Items]
2020	198,591
2019	407,891
2018	211,270
2017	209,484
2016	141,032
2015 and Prior	139,869
Financing Receivable, Revolving, Converted to Term Loan	26,018
Revolving Loans and Leases Converted to Term Loans and Leases	70
Total	1,334,225
Special Mention | Commercial | Commercial and industrial
Financing Receivable, Credit Quality Indicator [Line Items]
2020	9,996
2019	55,414
2018	34,345
2017	44,613
2016	14,564
2015 and Prior	13,127
Financing Receivable, Revolving, Converted to Term Loan	142,520
Revolving Loans and Leases Converted to Term Loans and Leases	0
Total	314,579
Special Mention | Commercial | Commercial real estate
Financing Receivable, Credit Quality Indicator [Line Items]
2020	289
2019	100,532
2018	55,678
2017	168,496
2016	62,608
2015 and Prior	102,896
Financing Receivable, Revolving, Converted to Term Loan	0
Revolving Loans and Leases Converted to Term Loans and Leases	0
Total	490,499
Special Mention | Commercial | Lease financing
Financing Receivable, Credit Quality Indicator [Line Items]
2020	2,703
2019	11,432
2018	4,687
2017	5,731
2016	2,469
2015 and Prior	1,658
Financing Receivable, Revolving, Converted to Term Loan	3,837
Revolving Loans and Leases Converted to Term Loans and Leases	5,299
Total	37,816
Special Mention | Consumer | Residential mortgage
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0
2019	0
2018	0
2017	0
2016	161
2015 and Prior	214
Financing Receivable, Revolving, Converted to Term Loan	0
Revolving Loans and Leases Converted to Term Loans and Leases	0
Total	375
Substandard | Commercial | Commercial and industrial
Financing Receivable, Credit Quality Indicator [Line Items]
2020	7,238
2019	51,459
2018	88,920
2017	36,442
2016	19,116
2015 and Prior	23,474
Financing Receivable, Revolving, Converted to Term Loan	97,984
Revolving Loans and Leases Converted to Term Loans and Leases	113
Total	324,746
Substandard | Commercial | Commercial real estate
Financing Receivable, Credit Quality Indicator [Line Items]
2020	1,056
2019	5,129
2018	34,754
2017	119,637
2016	43,004
2015 and Prior	90,174
Financing Receivable, Revolving, Converted to Term Loan	0
Revolving Loans and Leases Converted to Term Loans and Leases	0
Total	293,754
Substandard | Commercial | Lease financing
Financing Receivable, Credit Quality Indicator [Line Items]
2020	5,428
2019	11,672
2018	15,082
2017	9,305
2016	5,501
2015 and Prior	5,926
Financing Receivable, Revolving, Converted to Term Loan	418
Revolving Loans and Leases Converted to Term Loans and Leases	3,104
Total	56,436
Substandard | Consumer | Residential mortgage
Financing Receivable, Credit Quality Indicator [Line Items]
2020	677
2019	3,076
2018	3,387
2017	2,488
2016	3,173
2015 and Prior	58,679
Financing Receivable, Revolving, Converted to Term Loan	0
Revolving Loans and Leases Converted to Term Loans and Leases	0
Total	71,480
Substandard | Consumer | Home equity
Financing Receivable, Credit Quality Indicator [Line Items]
2020	698
2019	1,753
2018	580
2017	483
2016	569
2015 and Prior	7,181
Financing Receivable, Revolving, Converted to Term Loan	50,379
Revolving Loans and Leases Converted to Term Loans and Leases	1,442
Total	63,085
Substandard | Consumer | Consumer installment
Financing Receivable, Credit Quality Indicator [Line Items]
2020	397
2019	1,262
2018	1,382
2017	1,062
2016	547
2015 and Prior	1,860
Financing Receivable, Revolving, Converted to Term Loan	469
Revolving Loans and Leases Converted to Term Loans and Leases	0
Total	6,979
Financial Asset, Equal to or Greater than 90 Days Past Due | Impaired Loans With Valuation Allowance
Financing Receivable, Credit Quality Indicator [Line Items]
2020	366
2019	1,126
2018	697
2017	1,312
2016	482
2015 and Prior	3,872
Financing Receivable, Revolving, Converted to Term Loan	401
Revolving Loans and Leases Converted to Term Loans and Leases	0
Total	$ 8,256