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, 2025	Mar. 31, 2024
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	$ 254	$ 207
% of Total Class	0.21%	0.18%
Commercial
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	$ 224	$ 170
% of Total Class	0.31%	0.24%
Commercial | Term Extension
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	$ 87	$ 116
Commercial | Term Extension and Payment Delay
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	30	0
Commercial | Payment Delay
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	107	53
Commercial | Other
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	0	1
Commercial | Commercial and industrial loans
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	$ 121	$ 153
% of Total Class	0.23%	0.29%
Commercial | Commercial and industrial loans | Term Extension
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	$ 50	$ 99
Commercial | Commercial and industrial loans | Term Extension and Payment Delay
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	6	0
Commercial | Commercial and industrial loans | Payment Delay
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	65	53
Commercial | Commercial and industrial loans | Other
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	0	1
Commercial | Commercial mortgage owner-occupied loans
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	$ 29	$ 12
% of Total Class	0.47%	0.22%
Commercial | Commercial mortgage owner-occupied loans | Term Extension
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	$ 5	$ 12
Commercial | Commercial mortgage owner-occupied loans | Term Extension and Payment Delay
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	24	0
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	$ 24	$ 5
% of Total Class	0.39%	0.08%
Commercial | Commercial mortgage nonowner-occupied loans | Term Extension
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	$ 24	$ 5
Commercial | Commercial mortgage nonowner-occupied loans | Term Extension and Payment Delay
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	0	0
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	0
Commercial | Commercial construction loans
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	$ 50	$ 0
% of Total Class	0.84%	0.00%
Commercial | Commercial construction loans | Term Extension
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	$ 8	$ 0
Commercial | Commercial construction loans | Term Extension and Payment Delay
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	0	0
Commercial | Commercial construction loans | Payment Delay
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	42	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	$ 18	$ 26
% of Total Class	0.10%	0.15%
Residential Mortgage | Term Extension and Payment Delay
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	$ 16	$ 22
% of Total Class	0.09%	0.13%
Residential Mortgage | Payment Delay
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	$ 0	$ 2
% of Total Class	0.00%	0.01%
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	$ 12	$ 11
% of Total Class	0.04%	0.04%
Consumer | Payment Delay
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	$ 2	$ 1
Consumer | Interest Rate Reduction
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	7	8
Consumer | Term Extension, Interest Rate Reduction and Payment Delay
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	3	2
Consumer | Home equity
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	$ 4	$ 3
% of Total Class	0.09%	0.08%
Consumer | Home equity | Payment Delay
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	$ 0	$ 0
Consumer | Home equity | Interest Rate Reduction
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	1	1
Consumer | Home equity | Term Extension, Interest Rate Reduction and Payment Delay
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	3	2
Consumer | Credit card
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	$ 6	$ 7
% of Total Class	0.36%	0.40%
Consumer | Credit card | Payment Delay
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	$ 0	$ 0
Consumer | Credit card | Interest Rate Reduction
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	6	7
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%	0.04%
Consumer | Other consumer loans | Payment Delay
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	$ 1	$ 1
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 | Term Extension, Interest Rate Reduction and Payment Delay
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	0	0
Consumer | Solar energy installation loans
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	$ 1	$ 0
% of Total Class	0.02%	0.00%
Consumer | Solar energy installation loans | Payment Delay
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	$ 1	$ 0
Consumer | Solar energy installation loans | Interest Rate Reduction
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	0	0
Consumer | Solar energy installation loans | Term Extension, Interest Rate Reduction and Payment Delay
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	$ 0	$ 0