Loans and ACL - Loans Modified During Period That Were in Payment Default (Details) $ in Millions	6 Months Ended
	Jun. 30, 2023 USD ($)
Financing Receivable, Modified, Subsequent Default [Line Items]
Modifications Made in the Current Period That Were in Payment Default	$ 82
Renewals
Financing Receivable, Modified, Subsequent Default [Line Items]
Modifications Made in the Current Period That Were in Payment Default	33
Term Extensions
Financing Receivable, Modified, Subsequent Default [Line Items]
Modifications Made in the Current Period That Were in Payment Default	5
Capitalizations
Financing Receivable, Modified, Subsequent Default [Line Items]
Modifications Made in the Current Period That Were in Payment Default	3
Payment Delays
Financing Receivable, Modified, Subsequent Default [Line Items]
Modifications Made in the Current Period That Were in Payment Default	18
Combination - Capitalization and Term Extension
Financing Receivable, Modified, Subsequent Default [Line Items]
Modifications Made in the Current Period That Were in Payment Default	14
Combination - Capitalization, Interest Rate and Term Extension
Financing Receivable, Modified, Subsequent Default [Line Items]
Modifications Made in the Current Period That Were in Payment Default	2
Other
Financing Receivable, Modified, Subsequent Default [Line Items]
Modifications Made in the Current Period That Were in Payment Default	7
Commercial: | Commercial and industrial
Financing Receivable, Modified, Subsequent Default [Line Items]
Modifications Made in the Current Period That Were in Payment Default	33
Commercial: | Commercial and industrial | Renewals
Financing Receivable, Modified, Subsequent Default [Line Items]
Modifications Made in the Current Period That Were in Payment Default	33
Commercial: | Commercial and industrial | Term Extensions
Financing Receivable, Modified, Subsequent Default [Line Items]
Modifications Made in the Current Period That Were in Payment Default	0
Commercial: | Commercial and industrial | Capitalizations
Financing Receivable, Modified, Subsequent Default [Line Items]
Modifications Made in the Current Period That Were in Payment Default	0
Commercial: | Commercial and industrial | Payment Delays
Financing Receivable, Modified, Subsequent Default [Line Items]
Modifications Made in the Current Period That Were in Payment Default	0
Commercial: | Commercial and industrial | Combination - Capitalization and Term Extension
Financing Receivable, Modified, Subsequent Default [Line Items]
Modifications Made in the Current Period That Were in Payment Default	0
Commercial: | Commercial and industrial | Combination - Capitalization, Interest Rate and Term Extension
Financing Receivable, Modified, Subsequent Default [Line Items]
Modifications Made in the Current Period That Were in Payment Default	0
Commercial: | Commercial and industrial | Other
Financing Receivable, Modified, Subsequent Default [Line Items]
Modifications Made in the Current Period That Were in Payment Default	0
Consumer: | Residential mortgage
Financing Receivable, Modified, Subsequent Default [Line Items]
Modifications Made in the Current Period That Were in Payment Default	44
Consumer: | Residential mortgage | Renewals
Financing Receivable, Modified, Subsequent Default [Line Items]
Modifications Made in the Current Period That Were in Payment Default	0
Consumer: | Residential mortgage | Term Extensions
Financing Receivable, Modified, Subsequent Default [Line Items]
Modifications Made in the Current Period That Were in Payment Default	5
Consumer: | Residential mortgage | Capitalizations
Financing Receivable, Modified, Subsequent Default [Line Items]
Modifications Made in the Current Period That Were in Payment Default	3
Consumer: | Residential mortgage | Payment Delays
Financing Receivable, Modified, Subsequent Default [Line Items]
Modifications Made in the Current Period That Were in Payment Default	18
Consumer: | Residential mortgage | Combination - Capitalization and Term Extension
Financing Receivable, Modified, Subsequent Default [Line Items]
Modifications Made in the Current Period That Were in Payment Default	14
Consumer: | Residential mortgage | Combination - Capitalization, Interest Rate and Term Extension
Financing Receivable, Modified, Subsequent Default [Line Items]
Modifications Made in the Current Period That Were in Payment Default	2
Consumer: | Residential mortgage | Other
Financing Receivable, Modified, Subsequent Default [Line Items]
Modifications Made in the Current Period That Were in Payment Default	2
Consumer: | Indirect auto
Financing Receivable, Modified, Subsequent Default [Line Items]
Modifications Made in the Current Period That Were in Payment Default	3
Consumer: | Indirect auto | Renewals
Financing Receivable, Modified, Subsequent Default [Line Items]
Modifications Made in the Current Period That Were in Payment Default	0
Consumer: | Indirect auto | Term Extensions
Financing Receivable, Modified, Subsequent Default [Line Items]
Modifications Made in the Current Period That Were in Payment Default	0
Consumer: | Indirect auto | Capitalizations
Financing Receivable, Modified, Subsequent Default [Line Items]
Modifications Made in the Current Period That Were in Payment Default	0
Consumer: | Indirect auto | Payment Delays
Financing Receivable, Modified, Subsequent Default [Line Items]
Modifications Made in the Current Period That Were in Payment Default	0
Consumer: | Indirect auto | Combination - Capitalization and Term Extension
Financing Receivable, Modified, Subsequent Default [Line Items]
Modifications Made in the Current Period That Were in Payment Default	0
Consumer: | Indirect auto | Combination - Capitalization, Interest Rate and Term Extension
Financing Receivable, Modified, Subsequent Default [Line Items]
Modifications Made in the Current Period That Were in Payment Default	0
Consumer: | Indirect auto | Other
Financing Receivable, Modified, Subsequent Default [Line Items]
Modifications Made in the Current Period That Were in Payment Default	3
Consumer: | Home equity
Financing Receivable, Modified, Subsequent Default [Line Items]
Modifications Made in the Current Period That Were in Payment Default	1
Consumer: | Home equity | Renewals
Financing Receivable, Modified, Subsequent Default [Line Items]
Modifications Made in the Current Period That Were in Payment Default	0
Consumer: | Home equity | Term Extensions
Financing Receivable, Modified, Subsequent Default [Line Items]
Modifications Made in the Current Period That Were in Payment Default	0
Consumer: | Home equity | Capitalizations
Financing Receivable, Modified, Subsequent Default [Line Items]
Modifications Made in the Current Period That Were in Payment Default	0
Consumer: | Home equity | Payment Delays
Financing Receivable, Modified, Subsequent Default [Line Items]
Modifications Made in the Current Period That Were in Payment Default	0
Consumer: | Home equity | Combination - Capitalization and Term Extension
Financing Receivable, Modified, Subsequent Default [Line Items]
Modifications Made in the Current Period That Were in Payment Default	0
Consumer: | Home equity | Combination - Capitalization, Interest Rate and Term Extension
Financing Receivable, Modified, Subsequent Default [Line Items]
Modifications Made in the Current Period That Were in Payment Default	0
Consumer: | Home equity | Other
Financing Receivable, Modified, Subsequent Default [Line Items]
Modifications Made in the Current Period That Were in Payment Default	1
Credit card
Financing Receivable, Modified, Subsequent Default [Line Items]
Modifications Made in the Current Period That Were in Payment Default	1
Credit card | Renewals
Financing Receivable, Modified, Subsequent Default [Line Items]
Modifications Made in the Current Period That Were in Payment Default	0
Credit card | Term Extensions
Financing Receivable, Modified, Subsequent Default [Line Items]
Modifications Made in the Current Period That Were in Payment Default	0
Credit card | Capitalizations
Financing Receivable, Modified, Subsequent Default [Line Items]
Modifications Made in the Current Period That Were in Payment Default	0
Credit card | Payment Delays
Financing Receivable, Modified, Subsequent Default [Line Items]
Modifications Made in the Current Period That Were in Payment Default	0
Credit card | Combination - Capitalization and Term Extension
Financing Receivable, Modified, Subsequent Default [Line Items]
Modifications Made in the Current Period That Were in Payment Default	0
Credit card | Combination - Capitalization, Interest Rate and Term Extension
Financing Receivable, Modified, Subsequent Default [Line Items]
Modifications Made in the Current Period That Were in Payment Default	0
Credit card | Other
Financing Receivable, Modified, Subsequent Default [Line Items]
Modifications Made in the Current Period That Were in Payment Default	$ 1