Loans and ACL - Types of Modifications and Allowance at Period End (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2023	Dec. 31, 2022
Financing Receivable, Modifications [Line Items]
Financing Receivable, Troubled Debt Restructuring		$ 855	$ 2,200
Commercial: | Commercial and industrial
Financing Receivable, Modifications [Line Items]
Financing Receivable, Troubled Debt Restructuring		441
Commercial: | CRE
Financing Receivable, Modifications [Line Items]
Financing Receivable, Troubled Debt Restructuring		174
Commercial: | Commercial construction
Financing Receivable, Modifications [Line Items]
Financing Receivable, Troubled Debt Restructuring		1
Consumer: | Residential mortgage
Financing Receivable, Modifications [Line Items]
Financing Receivable, Troubled Debt Restructuring		203
Consumer: | Home equity
Financing Receivable, Modifications [Line Items]
Financing Receivable, Troubled Debt Restructuring		3
Consumer: | Indirect auto
Financing Receivable, Modifications [Line Items]
Financing Receivable, Troubled Debt Restructuring		21
Consumer: | Other consumer
Financing Receivable, Modifications [Line Items]
Financing Receivable, Troubled Debt Restructuring		7
Credit card
Financing Receivable, Modifications [Line Items]
Financing Receivable, Troubled Debt Restructuring		5
Structure
Financing Receivable, Modifications [Line Items]
Financing Receivable, Troubled Debt Restructuring		90
Structure | Commercial: | Commercial and industrial
Financing Receivable, Modifications [Line Items]
Financing Receivable, Troubled Debt Restructuring		51
Structure | Commercial: | CRE
Financing Receivable, Modifications [Line Items]
Financing Receivable, Troubled Debt Restructuring		0
Structure | Commercial: | Commercial construction
Financing Receivable, Modifications [Line Items]
Financing Receivable, Troubled Debt Restructuring		0
Structure | Consumer: | Residential mortgage
Financing Receivable, Modifications [Line Items]
Financing Receivable, Troubled Debt Restructuring		29
Structure | Consumer: | Home equity
Financing Receivable, Modifications [Line Items]
Financing Receivable, Troubled Debt Restructuring		0
Structure | Consumer: | Indirect auto
Financing Receivable, Modifications [Line Items]
Financing Receivable, Troubled Debt Restructuring		5
Structure | Consumer: | Other consumer
Financing Receivable, Modifications [Line Items]
Financing Receivable, Troubled Debt Restructuring		5
Structure | Credit card
Financing Receivable, Modifications [Line Items]
Financing Receivable, Troubled Debt Restructuring		$ 0
Newly Designated TDRs | Commercial:
Financing Receivable, Modifications [Line Items]
Related ALLL at Period End	$ 0
Financing Receivable, Troubled Debt Restructuring, Premodification	10
Newly Designated TDRs | Consumer:
Financing Receivable, Modifications [Line Items]
Related ALLL at Period End	15
Financing Receivable, Troubled Debt Restructuring, Premodification	329
Newly Designated TDRs | Credit card
Financing Receivable, Modifications [Line Items]
Related ALLL at Period End	1
Financing Receivable, Troubled Debt Restructuring, Premodification	2
Newly Designated TDRs | Rate | Commercial:
Financing Receivable, Modifications [Line Items]
TDRs	0
Newly Designated TDRs | Rate | Consumer:
Financing Receivable, Modifications [Line Items]
TDRs	148
Newly Designated TDRs | Rate | Credit card
Financing Receivable, Modifications [Line Items]
TDRs	2
Newly Designated TDRs | Structure | Commercial:
Financing Receivable, Modifications [Line Items]
TDRs	8
Newly Designated TDRs | Structure | Consumer:
Financing Receivable, Modifications [Line Items]
TDRs	191
Newly Designated TDRs | Structure | Credit card
Financing Receivable, Modifications [Line Items]
TDRs	0
Re-Modification of Previously Designated TDRs | Rate
Financing Receivable, Modifications [Line Items]
TDRs	21
Re-Modification of Previously Designated TDRs | Structure
Financing Receivable, Modifications [Line Items]
TDRs	$ 11
Performing
Financing Receivable, Modifications [Line Items]
Financing Receivable, Troubled Debt Restructuring			1,986
Performing | Commercial: | Commercial and industrial
Financing Receivable, Modifications [Line Items]
Financing Receivable, Troubled Debt Restructuring			136
Performing | Commercial: | CRE
Financing Receivable, Modifications [Line Items]
Financing Receivable, Troubled Debt Restructuring			5
Performing | Commercial: | Commercial construction
Financing Receivable, Modifications [Line Items]
Financing Receivable, Troubled Debt Restructuring			1
Performing | Consumer: | Residential mortgage
Financing Receivable, Modifications [Line Items]
Financing Receivable, Troubled Debt Restructuring			1,252
Performing | Consumer: | Home equity
Financing Receivable, Modifications [Line Items]
Financing Receivable, Troubled Debt Restructuring			51
Performing | Consumer: | Indirect auto
Financing Receivable, Modifications [Line Items]
Financing Receivable, Troubled Debt Restructuring			462
Performing | Consumer: | Other consumer
Financing Receivable, Modifications [Line Items]
Financing Receivable, Troubled Debt Restructuring			31
Performing | Consumer: | Student
Financing Receivable, Modifications [Line Items]
Financing Receivable, Troubled Debt Restructuring			30
Performing | Credit card
Financing Receivable, Modifications [Line Items]
Financing Receivable, Troubled Debt Restructuring			$ 18