Credit Quality and the Allowance for Loan and Lease Losses - Summary of Loans That Were Modified for Borrowers Experiencing Financial Difficulty (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
	Sep. 30, 2023	Sep. 30, 2023
Financing Receivable, Recorded Investment, Past Due
Financing receivable, excluding accrued interest, modified in period, amount	$ 171	$ 484
Current
Financing Receivable, Recorded Investment, Past Due
Financing receivable, excluding accrued interest, modified in period, amount	163	461
30-89 days past due
Financing Receivable, Recorded Investment, Past Due
Financing receivable, excluding accrued interest, modified in period, amount	7	17
90 Days or More
Financing Receivable, Recorded Investment, Past Due
Financing receivable, excluding accrued interest, modified in period, amount	1	6
Commercial
Financing Receivable, Recorded Investment, Past Due
Financing receivable, excluding accrued interest, modified in period, amount	124	355
Commercial | Commercial and industrial loans
Financing Receivable, Recorded Investment, Past Due
Financing receivable, excluding accrued interest, modified in period, amount	101	191
Commercial | Commercial and industrial loans | Current
Financing Receivable, Recorded Investment, Past Due
Financing receivable, excluding accrued interest, modified in period, amount	101	191
Commercial | Commercial and industrial loans | 30-89 days past due
Financing Receivable, Recorded Investment, Past Due
Financing receivable, excluding accrued interest, modified in period, amount	0	0
Commercial | Commercial and industrial loans | 90 Days or More
Financing Receivable, Recorded Investment, Past Due
Financing receivable, excluding accrued interest, modified in period, amount	0	0
Commercial | Commercial mortgage owner-occupied loans
Financing Receivable, Recorded Investment, Past Due
Financing receivable, excluding accrued interest, modified in period, amount	3	24
Commercial | Commercial mortgage owner-occupied loans | Current
Financing Receivable, Recorded Investment, Past Due
Financing receivable, excluding accrued interest, modified in period, amount	3	23
Commercial | Commercial mortgage owner-occupied loans | 30-89 days past due
Financing Receivable, Recorded Investment, Past Due
Financing receivable, excluding accrued interest, modified in period, amount	0	1
Commercial | Commercial mortgage owner-occupied loans | 90 Days or More
Financing Receivable, Recorded Investment, Past Due
Financing receivable, excluding accrued interest, modified in period, amount	0	0
Commercial | Commercial mortgage nonowner-occupied loans
Financing Receivable, Recorded Investment, Past Due
Financing receivable, excluding accrued interest, modified in period, amount	1	24
Commercial | Commercial mortgage nonowner-occupied loans | Current
Financing Receivable, Recorded Investment, Past Due
Financing receivable, excluding accrued interest, modified in period, amount	1	24
Commercial | Commercial mortgage nonowner-occupied loans | 30-89 days past due
Financing Receivable, Recorded Investment, Past Due
Financing receivable, excluding accrued interest, modified in period, amount	0	0
Commercial | Commercial mortgage nonowner-occupied loans | 90 Days or More
Financing Receivable, Recorded Investment, Past Due
Financing receivable, excluding accrued interest, modified in period, amount	0	0
Commercial | Commercial construction loans
Financing Receivable, Recorded Investment, Past Due
Financing receivable, excluding accrued interest, modified in period, amount	19	116
Commercial | Commercial construction loans | Current
Financing Receivable, Recorded Investment, Past Due
Financing receivable, excluding accrued interest, modified in period, amount	19	116
Commercial | Commercial construction loans | 30-89 days past due
Financing Receivable, Recorded Investment, Past Due
Financing receivable, excluding accrued interest, modified in period, amount	0	0
Commercial | Commercial construction loans | 90 Days or More
Financing Receivable, Recorded Investment, Past Due
Financing receivable, excluding accrued interest, modified in period, amount	0	0
Residential Mortgage
Financing Receivable, Recorded Investment, Past Due
Financing receivable, excluding accrued interest, modified in period, amount	31	89
Residential Mortgage | Current
Financing Receivable, Recorded Investment, Past Due
Financing receivable, excluding accrued interest, modified in period, amount	27	74
Residential Mortgage | 30-89 days past due
Financing Receivable, Recorded Investment, Past Due
Financing receivable, excluding accrued interest, modified in period, amount	4	12
Residential Mortgage | 90 Days or More
Financing Receivable, Recorded Investment, Past Due
Financing receivable, excluding accrued interest, modified in period, amount	0	3
Consumer
Financing Receivable, Recorded Investment, Past Due
Financing receivable, excluding accrued interest, modified in period, amount	16	40
Consumer | Home equity
Financing Receivable, Recorded Investment, Past Due
Financing receivable, excluding accrued interest, modified in period, amount	5	12
Consumer | Home equity | Current
Financing Receivable, Recorded Investment, Past Due
Financing receivable, excluding accrued interest, modified in period, amount	5	12
Consumer | Home equity | 30-89 days past due
Financing Receivable, Recorded Investment, Past Due
Financing receivable, excluding accrued interest, modified in period, amount	0	0
Consumer | Home equity | 90 Days or More
Financing Receivable, Recorded Investment, Past Due
Financing receivable, excluding accrued interest, modified in period, amount	0	0
Consumer | Credit card
Financing Receivable, Recorded Investment, Past Due
Financing receivable, excluding accrued interest, modified in period, amount	9	23
Consumer | Credit card | Current
Financing Receivable, Recorded Investment, Past Due
Financing receivable, excluding accrued interest, modified in period, amount	5	16
Consumer | Credit card | 30-89 days past due
Financing Receivable, Recorded Investment, Past Due
Financing receivable, excluding accrued interest, modified in period, amount	3	4
Consumer | Credit card | 90 Days or More
Financing Receivable, Recorded Investment, Past Due
Financing receivable, excluding accrued interest, modified in period, amount	1	3
Consumer | Other consumer loans
Financing Receivable, Recorded Investment, Past Due
Financing receivable, excluding accrued interest, modified in period, amount	2	5
Consumer | Other consumer loans | Current
Financing Receivable, Recorded Investment, Past Due
Financing receivable, excluding accrued interest, modified in period, amount	2	5
Consumer | Other consumer loans | 30-89 days past due
Financing Receivable, Recorded Investment, Past Due
Financing receivable, excluding accrued interest, modified in period, amount	0	0
Consumer | Other consumer loans | 90 Days or More
Financing Receivable, Recorded Investment, Past Due
Financing receivable, excluding accrued interest, modified in period, amount	$ 0	$ 0