Credit Quality and the Allowance for Loan and Lease Losses - Summary of Amortized Cost Basis of Loans Modified for Borrowers Experiencing Financial Difficulty (Details) $ in Millions	12 Months Ended
	Dec. 31, 2023 USD ($)
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	$ 615
Current
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	516
30-89 days past due
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	31
90 Days or More
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	68
Commercial Portfolio Segment
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	$ 453
% of Total Class	0.62%
Commercial Portfolio Segment | Term Extension
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	$ 361
Commercial Portfolio Segment | Interest Rate Reduction
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	1
Commercial Portfolio Segment | Payment Delay
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	56
Commercial Portfolio Segment | Term Extension and Interest Rate Reduction
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	4
Commercial Portfolio Segment | Term Extension and Payment Delay
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	31
Commercial Portfolio Segment | Commercial and industrial loans
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	$ 245
% of Total Class	0.46%
Commercial Portfolio Segment | Commercial and industrial loans | Current
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	$ 184
Commercial Portfolio Segment | Commercial and industrial loans | 30-89 days past due
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	9
Commercial Portfolio Segment | Commercial and industrial loans | 90 Days or More
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	52
Commercial Portfolio Segment | Commercial and industrial loans | Term Extension
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	155
Commercial Portfolio Segment | Commercial and industrial loans | Interest Rate Reduction
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	1
Commercial Portfolio Segment | Commercial and industrial loans | Payment Delay
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	56
Commercial Portfolio Segment | Commercial and industrial loans | Term Extension and Interest Rate Reduction
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	2
Commercial Portfolio Segment | Commercial and industrial loans | Term Extension and Payment Delay
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	31
Commercial Portfolio Segment | Commercial mortgage owner-occupied loans
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	$ 27
% of Total Class	0.52%
Commercial Portfolio Segment | Commercial mortgage owner-occupied loans | Current
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	$ 26
Commercial Portfolio Segment | Commercial mortgage owner-occupied loans | 30-89 days past due
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	0
Commercial Portfolio Segment | Commercial mortgage owner-occupied loans | 90 Days or More
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	1
Commercial Portfolio Segment | Commercial mortgage owner-occupied loans | Term Extension
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	27
Commercial Portfolio Segment | Commercial mortgage owner-occupied loans | Interest Rate Reduction
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	0
Commercial Portfolio Segment | Commercial mortgage owner-occupied loans | Payment Delay
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	0
Commercial Portfolio Segment | Commercial mortgage owner-occupied loans | Term Extension and Interest Rate Reduction
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	0
Commercial Portfolio Segment | Commercial mortgage owner-occupied loans | Term Extension and Payment Delay
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	0
Commercial Portfolio Segment | Commercial mortgage nonowner-occupied loans
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	$ 68
% of Total Class	1.12%
Commercial Portfolio Segment | Commercial mortgage nonowner-occupied loans | Current
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	$ 68
Commercial Portfolio Segment | Commercial mortgage nonowner-occupied loans | 30-89 days past due
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	0
Commercial Portfolio Segment | Commercial mortgage nonowner-occupied loans | 90 Days or More
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	0
Commercial Portfolio Segment | Commercial mortgage nonowner-occupied loans | Term Extension
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	66
Commercial Portfolio Segment | Commercial mortgage nonowner-occupied loans | Interest Rate Reduction
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	0
Commercial Portfolio Segment | Commercial mortgage nonowner-occupied loans | Payment Delay
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	0
Commercial Portfolio Segment | Commercial mortgage nonowner-occupied loans | Term Extension and Interest Rate Reduction
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	2
Commercial Portfolio Segment | Commercial mortgage nonowner-occupied loans | Term Extension and Payment Delay
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	0
Commercial Portfolio Segment | Commercial construction loans
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	$ 113
% of Total Class	2.01%
Commercial Portfolio Segment | Commercial construction loans | Current
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	$ 113
Commercial Portfolio Segment | Commercial construction loans | 30-89 days past due
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	0
Commercial Portfolio Segment | Commercial construction loans | 90 Days or More
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	0
Commercial Portfolio Segment | Commercial construction loans | Term Extension
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	113
Commercial Portfolio Segment | Commercial construction loans | Interest Rate Reduction
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	0
Commercial Portfolio Segment | Commercial construction loans | Payment Delay
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	0
Commercial Portfolio Segment | Commercial construction loans | Term Extension and Interest Rate Reduction
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	0
Commercial Portfolio Segment | Commercial construction loans | Term Extension and Payment Delay
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	0
Residential mortgage loans
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	$ 113
% of Total Class	0.66%
Residential mortgage loans | Current
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	$ 86
Residential mortgage loans | 30-89 days past due
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	15
Residential mortgage loans | 90 Days or More
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	12
Residential mortgage loans | Payment Delay
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	$ 18
% of Total Class	0.11%
Residential mortgage loans | Term Extension and Payment Delay
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	$ 91
% of Total Class	0.53%
Residential mortgage loans | Term Extension, Interest Rate Reduction and Payment Delay
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	$ 4
% of Total Class	0.02%
Consumer
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	$ 49
% of Total Class	0.18%
Consumer | Interest Rate Reduction
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	$ 31
Consumer | Payment Delay
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	7
Consumer | Interest Rate Reduction and Payment Delay
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	1
Consumer | Term Extension and Payment Delay
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	2
Consumer | Term Extension, Interest Rate Reduction and Payment Delay
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	8
Consumer | Home equity
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	$ 16
% of Total Class	0.41%
Consumer | Home equity | Current
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	$ 14
Consumer | Home equity | 30-89 days past due
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	2
Consumer | Home equity | 90 Days or More
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	0
Consumer | Home equity | Interest Rate Reduction
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	4
Consumer | Home equity | Payment Delay
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	1
Consumer | Home equity | Interest Rate Reduction and Payment Delay
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	1
Consumer | Home equity | Term Extension and Payment Delay
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	2
Consumer | Home equity | Term Extension, Interest Rate Reduction and Payment Delay
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	8
Consumer | Credit card
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	$ 27
% of Total Class	1.45%
Consumer | Credit card | Current
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	$ 19
Consumer | Credit card | 30-89 days past due
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	5
Consumer | Credit card | 90 Days or More
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	3
Consumer | Credit card | Interest Rate Reduction
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	27
Consumer | Credit card | Payment Delay
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	0
Consumer | Credit card | Interest Rate Reduction and Payment Delay
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	0
Consumer | Credit card | Term Extension and Payment Delay
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	0
Consumer | Credit card | Term Extension, Interest Rate Reduction and Payment Delay
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	0
Consumer | Other consumer loans:
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	$ 6
% of Total Class	0.09%
Consumer | Other consumer loans: | Current
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	$ 6
Consumer | Other consumer loans: | 30-89 days past due
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	0
Consumer | Other consumer loans: | 90 Days or More
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	0
Consumer | Other consumer loans: | Interest Rate Reduction
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	0
Consumer | Other consumer loans: | Payment Delay
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	6
Consumer | Other consumer loans: | Interest Rate Reduction and Payment Delay
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	0
Consumer | Other consumer loans: | Term Extension and Payment Delay
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	0
Consumer | Other consumer loans: | Term Extension, Interest Rate Reduction and Payment Delay
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	$ 0