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	6 Months Ended
	Jun. 30, 2023	Jun. 30, 2023
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	$ 331	$ 444
Commercial
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	$ 282	$ 358
% of Total Class	0.37%	0.47%
Commercial | Term Extension
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	$ 275	$ 348
Commercial | Interest Rate Reduction
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	0	1
Commercial | Term Extension and Interest Rate Reduction
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	0	2
Commercial | Payment Deferral
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	7	7
Commercial | Commercial and industrial loans
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	$ 170	$ 191
% of Total Class	0.30%	0.34%
Commercial | Commercial and industrial loans | Term Extension
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	$ 163	$ 183
Commercial | Commercial and industrial loans | Interest Rate Reduction
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	0	1
Commercial | Commercial and industrial loans | Term Extension and Interest Rate Reduction
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	0	0
Commercial | Commercial and industrial loans | Payment Deferral
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	7	7
Commercial | Commercial mortgage owner-occupied loans
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	$ 40	$ 40
% of Total Class	0.74%	0.74%
Commercial | Commercial mortgage owner-occupied loans | Term Extension
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	$ 40	$ 40
Commercial | Commercial mortgage owner-occupied loans | Interest Rate Reduction
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	0	0
Commercial | Commercial mortgage owner-occupied loans | Term Extension and Interest Rate Reduction
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	0	0
Commercial | Commercial mortgage owner-occupied loans | Payment Deferral
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	$ 2	$ 26
% of Total Class	0.03%	0.44%
Commercial | Commercial mortgage nonowner-occupied loans | Term Extension
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	$ 2	$ 24
Commercial | Commercial mortgage nonowner-occupied loans | Interest Rate Reduction
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	0	0
Commercial | Commercial mortgage nonowner-occupied loans | Term Extension and Interest Rate Reduction
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	0	2
Commercial | Commercial mortgage nonowner-occupied loans | Payment Deferral
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	$ 70	$ 101
% of Total Class	1.28%	1.84%
Commercial | Commercial construction loans | Term Extension
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	$ 70	$ 101
Commercial | Commercial construction loans | Interest Rate Reduction
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	0	0
Commercial | Commercial construction loans | Term Extension and Interest Rate Reduction
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	0	0
Commercial | Commercial construction loans | Payment Deferral
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	$ 36	$ 59
% of Total Class	0.21%	0.34%
Residential Mortgage | Payment Deferral
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	$ 6	$ 14
% of Total Class	0.03%	0.08%
Residential Mortgage | Term Extension and Payment Deferral
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	$ 29	$ 42
% of Total Class	0.17%	0.24%
Residential Mortgage | Term Extension, Interest Rate Reduction and Payment Deferral
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	$ 1	$ 3
% of Total Class	0.01%	0.02%
Consumer
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	$ 13	$ 27
% of Total Class	0.05%	0.10%
Consumer | Interest Rate Reduction
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	$ 8	$ 18
Consumer | Payment Deferral
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	2	3
Consumer | Term Extension and Payment Deferral
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	1	2
Consumer | Term Extension, Interest Rate Reduction and Payment Deferral
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	2	4
Consumer | Home equity
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	$ 3	$ 7
% of Total Class	0.08%	0.18%
Consumer | Home equity | Interest Rate Reduction
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	$ 0	$ 1
Consumer | Home equity | Payment Deferral
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	0	0
Consumer | Home equity | Term Extension and Payment Deferral
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	1	2
Consumer | Home equity | Term Extension, Interest Rate Reduction and Payment Deferral
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	2	4
Consumer | Credit card
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	$ 8	$ 17
% of Total Class	0.44%	0.94%
Consumer | Credit card | Interest Rate Reduction
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	$ 8	$ 17
Consumer | Credit card | Payment Deferral
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	0	0
Consumer | Credit card | Term Extension and Payment Deferral
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	0	0
Consumer | Credit card | Term Extension, Interest Rate Reduction and Payment Deferral
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	$ 2	$ 3
% of Total Class	0.03%	0.05%
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 Deferral
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	2	3
Consumer | Other consumer loans | Term Extension and Payment Deferral
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 Deferral
Financing Receivable, Modifications
Financing receivable, excluding accrued interest, modified in period, amount	$ 0	$ 0