Allowance for Credit Losses and Credit Quality - Schedule of Nonaccrual Loans and Leases (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Financing Receivable, Allowance for Credit Loss [Line Items]
Total nonaccrual	$ 677,901	$ 677,302
Nonaccrual with no ACL	200,116	138,579
Financial Asset Originated | Commercial
Financing Receivable, Allowance for Credit Loss [Line Items]
Total nonaccrual	522,365	504,700
Nonaccrual with no ACL	196,253	134,976
Financial Asset Originated | Commercial | Commercial and industrial
Financing Receivable, Allowance for Credit Loss [Line Items]
Total nonaccrual	239,987	259,439
Nonaccrual with no ACL	45,371	55,773
Financial Asset Originated | Commercial | Commercial real estate
Financing Receivable, Allowance for Credit Loss [Line Items]
Total nonaccrual	188,420	154,439
Nonaccrual with no ACL	150,882	79,203
Financial Asset Originated | Commercial | Lease financing
Financing Receivable, Allowance for Credit Loss [Line Items]
Total nonaccrual	93,958	90,822
Nonaccrual with no ACL	0	0
Financial Asset Originated | Consumer
Financing Receivable, Allowance for Credit Loss [Line Items]
Total nonaccrual	155,536	172,602
Nonaccrual with no ACL	3,863	3,603
Financial Asset Originated | Consumer | Residential mortgage
Financing Receivable, Allowance for Credit Loss [Line Items]
Total nonaccrual	76,533	97,653
Nonaccrual with no ACL	0	49
Financial Asset Originated | Consumer | Home equity
Financing Receivable, Allowance for Credit Loss [Line Items]
Total nonaccrual	72,941	69,383
Nonaccrual with no ACL	358	23
Financial Asset Originated | Consumer | Consumer installment
Financing Receivable, Allowance for Credit Loss [Line Items]
Total nonaccrual	6,062	5,566
Nonaccrual with no ACL	$ 3,505	$ 3,531