Loans and ACL - Aging Analysis of Loans and Leases (Details) - USD ($) $ in Millions		Sep. 30, 2023		Dec. 31, 2022
Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss		$ 315,699		$ 325,991
Nonperforming		1,452		1,188
Total loans and leases		315,699		325,991
Financial Asset, Not Past Due
Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss		312,037		320,931
Financing Receivables 30 To 89 Days Past Due
Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss		1,636		2,267
Financial Asset, Equal to or Greater than 90 Days Past Due
Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss		574		1,605
Commercial: | Commercial and industrial
Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss		162,330		164,307
Nonperforming		561		398
Total loans and leases		162,330		164,307
Commercial: | Commercial and industrial | Financial Asset, Not Past Due
Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss		161,656		163,604
Commercial: | Commercial and industrial | Financing Receivables 30 To 89 Days Past Due
Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss		98		256
Commercial: | Commercial and industrial | Financial Asset, Equal to or Greater than 90 Days Past Due
Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss		15		49
Commercial: | CRE
Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss		22,736		22,676
Nonperforming		289		82
Total loans and leases		22,736		22,676
Commercial: | CRE | Financial Asset, Not Past Due
Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss		22,419		22,568
Commercial: | CRE | Financing Receivables 30 To 89 Days Past Due
Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss		28		25
Commercial: | CRE | Financial Asset, Equal to or Greater than 90 Days Past Due
Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss		0		1
Commercial: | Commercial construction
Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss		6,343		5,849
Nonperforming		29		0
Total loans and leases		6,343		5,849
Commercial: | Commercial construction | Financial Asset, Not Past Due
Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss		6,313		5,844
Commercial: | Commercial construction | Financing Receivables 30 To 89 Days Past Due
Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss		1		5
Commercial: | Commercial construction | Financial Asset, Equal to or Greater than 90 Days Past Due
Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss		0		0
Consumer: | Residential mortgage
Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss		56,013		56,645
Nonperforming		132		240
Total loans and leases		56,013		56,645
Consumer: | Residential mortgage | Financial Asset, Not Past Due
Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss		54,832		55,005
Consumer: | Residential mortgage | Financing Receivables 30 To 89 Days Past Due
Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss		563		614
Consumer: | Residential mortgage | Financial Asset, Equal to or Greater than 90 Days Past Due
Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss		486	[1]	786	[2]
Consumer: | Residential mortgage | Financial Asset, Equal to or Greater than 90 Days Past Due | Loans Insured or Guaranteed by US Government Authorities
Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss		456		759
Consumer: | Home equity
Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss		10,160		10,876
Nonperforming		123		135
Total loans and leases		10,160		10,876
Consumer: | Home equity | Financial Asset, Not Past Due
Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss		9,967		10,661
Consumer: | Home equity | Financing Receivables 30 To 89 Days Past Due
Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss		61		68
Consumer: | Home equity | Financial Asset, Equal to or Greater than 90 Days Past Due
Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss		9		12
Consumer: | Indirect auto
Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss		24,084		27,951
Nonperforming		266		289
Total loans and leases		24,084		27,951
Consumer: | Indirect auto | Financial Asset, Not Past Due
Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss		23,219		27,015
Consumer: | Indirect auto | Financing Receivables 30 To 89 Days Past Due
Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss		598		646
Consumer: | Indirect auto | Financial Asset, Equal to or Greater than 90 Days Past Due
Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss		1		1
Consumer: | Other consumer
Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss		29,105		27,533
Nonperforming		52		44
Total loans and leases		29,105		27,533
Consumer: | Other consumer | Financial Asset, Not Past Due
Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss		28,818		27,289
Consumer: | Other consumer | Financing Receivables 30 To 89 Days Past Due
Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss		219		187
Consumer: | Other consumer | Financial Asset, Equal to or Greater than 90 Days Past Due
Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss		16		13
Consumer: | Student
Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss				5,287
Nonperforming				0
Total loans and leases				5,287
Consumer: | Student | Financial Asset, Not Past Due
Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss				4,179
Consumer: | Student | Financing Receivables 30 To 89 Days Past Due
Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss				402
Consumer: | Student | Financial Asset, Equal to or Greater than 90 Days Past Due
Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss	[2]			706
Consumer: | Student | Financial Asset, Equal to or Greater than 90 Days Past Due | Loans Insured or Guaranteed by US Government Authorities
Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss				702
Credit card
Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss		4,928		4,867
Nonperforming		0		0
Total loans and leases		4,928		4,867
Credit card | Financial Asset, Not Past Due
Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss		4,813		4,766
Credit card | Financing Receivables 30 To 89 Days Past Due
Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss		68		64
Credit card | Financial Asset, Equal to or Greater than 90 Days Past Due
Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss		$ 47		$ 37

[1] (1)Includes government guaranteed loans of $456 million in the residential mortgage portfolio.

[2] (1)Includes government guaranteed loans of $759 million in the residential mortgage portfolio and $702 million in the student portfolio.