Credit Quality and the Allowance for Loan and Lease Losses - Summary of Amortized Cost Basis of Loans Modified for Borrowers Experiencing Financial Difficulty (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	$ 207	$ 202
% of Total Class	0.18%	0.16%
Commercial
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	$ 170	$ 163
% of Total Class	0.24%	0.21%
Commercial | Term Extension
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	$ 116	$ 159
Commercial | Payment Delay
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	53	0
Commercial | Other
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	1	4
Commercial | Commercial and industrial loans
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	$ 153	$ 106
% of Total Class	0.29%	0.18%
Commercial | Commercial and industrial loans | Term Extension
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	$ 99	$ 105
Commercial | Commercial and industrial loans | Payment Delay
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	53	0
Commercial | Commercial and industrial loans | Other
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	1	1
Commercial | Commercial mortgage owner-occupied loans
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	$ 12	$ 1
% of Total Class	0.22%	0.02%
Commercial | Commercial mortgage owner-occupied loans | Term Extension
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	$ 12	$ 1
Commercial | Commercial mortgage owner-occupied loans | Payment Delay
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	0	0
Commercial | Commercial mortgage owner-occupied loans | Other
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	0	0
Commercial | Commercial mortgage nonowner-occupied loans
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	$ 5	$ 25
% of Total Class	0.08%	0.43%
Commercial | Commercial mortgage nonowner-occupied loans | Term Extension
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	$ 5	$ 22
Commercial | Commercial mortgage nonowner-occupied loans | Payment Delay
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	0	0
Commercial | Commercial mortgage nonowner-occupied loans | Other
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	0	3
Commercial | Commercial construction loans
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	$ 0	$ 31
% of Total Class	0.00%	0.56%
Commercial | Commercial construction loans | Term Extension
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	$ 0	$ 31
Commercial | Commercial construction loans | Payment Delay
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	0	0
Commercial | Commercial construction loans | Other
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	0	0
Residential Mortgage
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	$ 26	$ 24
% of Total Class	0.15%	0.14%
Residential Mortgage | Payment Delay
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	$ 2	$ 8
% of Total Class	0.01%	0.05%
Residential Mortgage | Term Extension and Payment Delay
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	$ 22	$ 14
% of Total Class	0.13%	0.08%
Residential Mortgage | Term Extension, Interest Rate Reduction and Payment Delay
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	$ 2	$ 2
% of Total Class	0.01%	0.01%
Consumer
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	$ 11	$ 15
% of Total Class	0.04%	0.05%
Consumer | Interest Rate Reduction
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	$ 8	$ 10
Consumer | Payment Delay
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	1	1
Consumer | Term Extension and Payment Delay
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	0	1
Consumer | Term Extension, Interest Rate Reduction and Payment Delay
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	2	3
Consumer | Home equity
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	$ 3	$ 4
% of Total Class	0.08%	0.10%
Consumer | Home equity | Interest Rate Reduction
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	$ 1	$ 0
Consumer | Home equity | Payment Delay
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	0	0
Consumer | Home equity | Term Extension and Payment Delay
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	0	1
Consumer | Home equity | Term Extension, Interest Rate Reduction and Payment Delay
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	2	3
Consumer | Credit card
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	$ 7	$ 10
% of Total Class	0.40%	0.57%
Consumer | Credit card | Interest Rate Reduction
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	$ 7	$ 10
Consumer | Credit card | Payment Delay
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	0	0
Consumer | Credit card | Term Extension and Payment Delay
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	0	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	0
Consumer | Other consumer loans
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	$ 1	$ 1
% of Total Class	0.04%	0.02%
Consumer | Other consumer loans | Interest Rate Reduction
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	$ 0	$ 0
Consumer | Other consumer loans | Payment Delay
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	1	1
Consumer | Other consumer loans | Term Extension and Payment Delay
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	0	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	$ 0