Loans and ACL - Delinquency Status of Loans that Were Modified During the Period (Details) - USD ($) $ in Millions	Jun. 30, 2023	Dec. 31, 2022
Financing Receivable, Modified
Financing Receivable, Modified, Accumulated	$ 1,365	$ 2,200
Financial Asset, Not Past Due
Financing Receivable, Modified
Financing Receivable, Modified, Accumulated	1,184
Financing Receivables 30 To 89 Days Past Due
Financing Receivable, Modified
Financing Receivable, Modified, Accumulated	99
Financial Asset, Equal to or Greater than 90 Days Past Due
Financing Receivable, Modified
Financing Receivable, Modified, Accumulated	82
Nonperforming
Financing Receivable, Modified
Financing Receivable, Modified, Accumulated	361	$ 214
Nonperforming | Financial Asset, Not Past Due
Financing Receivable, Modified
Financing Receivable, Modified, Accumulated	291
Nonperforming | Financing Receivables 30 To 89 Days Past Due
Financing Receivable, Modified
Financing Receivable, Modified, Accumulated	23
Nonperforming | Financial Asset, Equal to or Greater than 90 Days Past Due
Financing Receivable, Modified
Financing Receivable, Modified, Accumulated	47
Commercial: | Commercial and industrial
Financing Receivable, Modified
Financing Receivable, Modified, Accumulated	564
Commercial: | Commercial and industrial | Financial Asset, Not Past Due
Financing Receivable, Modified
Financing Receivable, Modified, Accumulated	528
Commercial: | Commercial and industrial | Financing Receivables 30 To 89 Days Past Due
Financing Receivable, Modified
Financing Receivable, Modified, Accumulated	3
Commercial: | Commercial and industrial | Financial Asset, Equal to or Greater than 90 Days Past Due
Financing Receivable, Modified
Financing Receivable, Modified, Accumulated	33
Commercial: | CRE
Financing Receivable, Modified
Financing Receivable, Modified, Accumulated	187
Commercial: | CRE | Financial Asset, Not Past Due
Financing Receivable, Modified
Financing Receivable, Modified, Accumulated	187
Commercial: | CRE | Financing Receivables 30 To 89 Days Past Due
Financing Receivable, Modified
Financing Receivable, Modified, Accumulated	0
Commercial: | CRE | Financial Asset, Equal to or Greater than 90 Days Past Due
Financing Receivable, Modified
Financing Receivable, Modified, Accumulated	0
Commercial: | Commercial construction
Financing Receivable, Modified
Financing Receivable, Modified, Accumulated	3
Commercial: | Commercial construction | Financial Asset, Not Past Due
Financing Receivable, Modified
Financing Receivable, Modified, Accumulated	3
Commercial: | Commercial construction | Financing Receivables 30 To 89 Days Past Due
Financing Receivable, Modified
Financing Receivable, Modified, Accumulated	0
Commercial: | Commercial construction | Financial Asset, Equal to or Greater than 90 Days Past Due
Financing Receivable, Modified
Financing Receivable, Modified, Accumulated	0
Consumer: | Residential mortgage
Financing Receivable, Modified
Financing Receivable, Modified, Accumulated	403
Consumer: | Residential mortgage | Financial Asset, Not Past Due
Financing Receivable, Modified
Financing Receivable, Modified, Accumulated	282
Consumer: | Residential mortgage | Financing Receivables 30 To 89 Days Past Due
Financing Receivable, Modified
Financing Receivable, Modified, Accumulated	77
Consumer: | Residential mortgage | Financial Asset, Equal to or Greater than 90 Days Past Due
Financing Receivable, Modified
Financing Receivable, Modified, Accumulated	44
Consumer: | Home equity
Financing Receivable, Modified
Financing Receivable, Modified, Accumulated	7
Consumer: | Home equity | Financial Asset, Not Past Due
Financing Receivable, Modified
Financing Receivable, Modified, Accumulated	6
Consumer: | Home equity | Financing Receivables 30 To 89 Days Past Due
Financing Receivable, Modified
Financing Receivable, Modified, Accumulated	0
Consumer: | Home equity | Financial Asset, Equal to or Greater than 90 Days Past Due
Financing Receivable, Modified
Financing Receivable, Modified, Accumulated	1
Consumer: | Indirect auto
Financing Receivable, Modified
Financing Receivable, Modified, Accumulated	177
Consumer: | Indirect auto | Financial Asset, Not Past Due
Financing Receivable, Modified
Financing Receivable, Modified, Accumulated	157
Consumer: | Indirect auto | Financing Receivables 30 To 89 Days Past Due
Financing Receivable, Modified
Financing Receivable, Modified, Accumulated	17
Consumer: | Indirect auto | Financial Asset, Equal to or Greater than 90 Days Past Due
Financing Receivable, Modified
Financing Receivable, Modified, Accumulated	3
Consumer: | Other consumer
Financing Receivable, Modified
Financing Receivable, Modified, Accumulated	15
Consumer: | Other consumer | Financial Asset, Not Past Due
Financing Receivable, Modified
Financing Receivable, Modified, Accumulated	14
Consumer: | Other consumer | Financing Receivables 30 To 89 Days Past Due
Financing Receivable, Modified
Financing Receivable, Modified, Accumulated	1
Consumer: | Other consumer | Financial Asset, Equal to or Greater than 90 Days Past Due
Financing Receivable, Modified
Financing Receivable, Modified, Accumulated	0
Credit card
Financing Receivable, Modified
Financing Receivable, Modified, Accumulated	9
Credit card | Financial Asset, Not Past Due
Financing Receivable, Modified
Financing Receivable, Modified, Accumulated	7
Credit card | Financing Receivables 30 To 89 Days Past Due
Financing Receivable, Modified
Financing Receivable, Modified, Accumulated	1
Credit card | Financial Asset, Equal to or Greater than 90 Days Past Due
Financing Receivable, Modified
Financing Receivable, Modified, Accumulated	$ 1