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Credit Quality and the Allowance for Loan and Lease Losses - Summary of Gross Charge-Offs Within the Commercial Portfolio Segments, by Class and Vintage (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Financing Receivable, Modifications
Total	$ 522	$ 362	$ 344
Commercial Portfolio Segment
Financing Receivable, Modifications
2023	25
2022	7
2021	12
2020	1
2019	0
Prior	11
Revolving Loans	114
Revolving Loans Converted to Term Loans	0
Total	170	$ 131	$ 119
Commercial Portfolio Segment \| Commercial and industrial loans
Financing Receivable, Modifications
2023	25
2022	7
2021	12
2020	1
2019	0
Prior	11
Revolving Loans	112
Revolving Loans Converted to Term Loans	0
Total	168
Commercial Portfolio Segment \| Commercial mortgage owner-occupied loans
Financing Receivable, Modifications
2023	0
2022	0
2021	0
2020	0
2019	0
Prior	0
Revolving Loans	1
Revolving Loans Converted to Term Loans	0
Total	1
Commercial Portfolio Segment \| Commercial construction loans
Financing Receivable, Modifications
2023	0
2022	0
2021	0
2020	0
2019	0
Prior	0
Revolving Loans	1
Revolving Loans Converted to Term Loans	0
Total	$ 1