Loans and ACL - Summary of Loan Modifications (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2023	Dec. 31, 2022
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modified, Accumulated	$ 855	$ 2,200
Financing Receivable, Modified in Period, to Total Financing Receivables, Percentage	0.26%
Renewals
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modified, Accumulated	$ 494
Term Extensions
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modified, Accumulated	90
Capitalizations
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modified, Accumulated	32
Payment Delays
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modified, Accumulated	101
Combination - Interest Rate Reduction and Term Extension
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modified, Accumulated	9
Combination - Capitalization and Term Extension
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modified, Accumulated	92
Combination - Capitalization, Interest Rate and Term Extension
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modified, Accumulated	20
Other
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modified, Accumulated	17
Commercial: | Commercial and industrial
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modified, Accumulated	$ 441
Financing Receivable, Modified in Period, to Total Financing Receivables, Percentage	0.26%
Commercial: | Commercial and industrial | Renewals
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modified, Accumulated	$ 390
Commercial: | Commercial and industrial | Term Extensions
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modified, Accumulated	51
Commercial: | Commercial and industrial | Capitalizations
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modified, Accumulated	0
Commercial: | Commercial and industrial | Payment Delays
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modified, Accumulated	0
Commercial: | Commercial and industrial | Combination - Interest Rate Reduction and Term Extension
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modified, Accumulated	0
Commercial: | Commercial and industrial | Combination - Capitalization and Term Extension
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modified, Accumulated	0
Commercial: | Commercial and industrial | Combination - Capitalization, Interest Rate and Term Extension
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modified, Accumulated	0
Commercial: | Commercial and industrial | Other
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modified, Accumulated	0
Commercial: | CRE
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modified, Accumulated	$ 174
Financing Receivable, Modified in Period, to Total Financing Receivables, Percentage	0.77%
Commercial: | CRE | Renewals
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modified, Accumulated	$ 103
Commercial: | CRE | Term Extensions
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modified, Accumulated	0
Commercial: | CRE | Capitalizations
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modified, Accumulated	0
Commercial: | CRE | Payment Delays
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modified, Accumulated	71
Commercial: | CRE | Combination - Interest Rate Reduction and Term Extension
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modified, Accumulated	0
Commercial: | CRE | Combination - Capitalization and Term Extension
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modified, Accumulated	0
Commercial: | CRE | Combination - Capitalization, Interest Rate and Term Extension
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modified, Accumulated	0
Commercial: | CRE | Other
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modified, Accumulated	0
Commercial: | Commercial construction
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modified, Accumulated	$ 1
Financing Receivable, Modified in Period, to Total Financing Receivables, Percentage	0.02%
Commercial: | Commercial construction | Renewals
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modified, Accumulated	$ 1
Commercial: | Commercial construction | Term Extensions
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modified, Accumulated	0
Commercial: | Commercial construction | Capitalizations
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modified, Accumulated	0
Commercial: | Commercial construction | Payment Delays
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modified, Accumulated	0
Commercial: | Commercial construction | Combination - Interest Rate Reduction and Term Extension
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modified, Accumulated	0
Commercial: | Commercial construction | Combination - Capitalization and Term Extension
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modified, Accumulated	0
Commercial: | Commercial construction | Combination - Capitalization, Interest Rate and Term Extension
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modified, Accumulated	0
Commercial: | Commercial construction | Other
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modified, Accumulated	0
Consumer: | Residential mortgage
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modified, Accumulated	$ 203
Financing Receivable, Modified in Period, to Total Financing Receivables, Percentage	0.36%
Consumer: | Residential mortgage | Renewals
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modified, Accumulated	$ 0
Consumer: | Residential mortgage | Term Extensions
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modified, Accumulated	29
Consumer: | Residential mortgage | Capitalizations
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modified, Accumulated	32
Consumer: | Residential mortgage | Payment Delays
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modified, Accumulated	25
Consumer: | Residential mortgage | Combination - Interest Rate Reduction and Term Extension
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modified, Accumulated	1
Consumer: | Residential mortgage | Combination - Capitalization and Term Extension
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modified, Accumulated	92
Consumer: | Residential mortgage | Combination - Capitalization, Interest Rate and Term Extension
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modified, Accumulated	20
Consumer: | Residential mortgage | Other
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modified, Accumulated	4
Consumer: | Home equity
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modified, Accumulated	$ 3
Financing Receivable, Modified in Period, to Total Financing Receivables, Percentage	0.03%
Consumer: | Home equity | Renewals
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modified, Accumulated	$ 0
Consumer: | Home equity | Term Extensions
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modified, Accumulated	0
Consumer: | Home equity | Capitalizations
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modified, Accumulated	0
Consumer: | Home equity | Payment Delays
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modified, Accumulated	0
Consumer: | Home equity | Combination - Interest Rate Reduction and Term Extension
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modified, Accumulated	2
Consumer: | Home equity | Combination - Capitalization and Term Extension
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modified, Accumulated	0
Consumer: | Home equity | Combination - Capitalization, Interest Rate and Term Extension
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modified, Accumulated	0
Consumer: | Home equity | Other
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modified, Accumulated	1
Consumer: | Indirect auto
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modified, Accumulated	$ 21
Financing Receivable, Modified in Period, to Total Financing Receivables, Percentage	0.08%
Consumer: | Indirect auto | Renewals
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modified, Accumulated	$ 0
Consumer: | Indirect auto | Term Extensions
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modified, Accumulated	5
Consumer: | Indirect auto | Capitalizations
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modified, Accumulated	0
Consumer: | Indirect auto | Payment Delays
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modified, Accumulated	5
Consumer: | Indirect auto | Combination - Interest Rate Reduction and Term Extension
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modified, Accumulated	5
Consumer: | Indirect auto | Combination - Capitalization and Term Extension
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modified, Accumulated	0
Consumer: | Indirect auto | Combination - Capitalization, Interest Rate and Term Extension
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modified, Accumulated	0
Consumer: | Indirect auto | Other
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modified, Accumulated	6
Consumer: | Other consumer
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modified, Accumulated	$ 7
Financing Receivable, Modified in Period, to Total Financing Receivables, Percentage	0.03%
Consumer: | Other consumer | Renewals
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modified, Accumulated	$ 0
Consumer: | Other consumer | Term Extensions
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modified, Accumulated	5
Consumer: | Other consumer | Capitalizations
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modified, Accumulated	0
Consumer: | Other consumer | Payment Delays
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modified, Accumulated	0
Consumer: | Other consumer | Combination - Interest Rate Reduction and Term Extension
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modified, Accumulated	1
Consumer: | Other consumer | Combination - Capitalization and Term Extension
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modified, Accumulated	0
Consumer: | Other consumer | Combination - Capitalization, Interest Rate and Term Extension
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modified, Accumulated	0
Consumer: | Other consumer | Other
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modified, Accumulated	1
Credit card
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modified, Accumulated	$ 5
Financing Receivable, Modified in Period, to Total Financing Receivables, Percentage	0.10%
Credit card | Renewals
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modified, Accumulated	$ 0
Credit card | Term Extensions
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modified, Accumulated	0
Credit card | Capitalizations
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modified, Accumulated	0
Credit card | Payment Delays
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modified, Accumulated	0
Credit card | Combination - Interest Rate Reduction and Term Extension
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modified, Accumulated	0
Credit card | Combination - Capitalization and Term Extension
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modified, Accumulated	0
Credit card | Combination - Capitalization, Interest Rate and Term Extension
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modified, Accumulated	0
Credit card | Other
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modified, Accumulated	$ 5