Credit Quality and the Allowance for Loan and Lease Losses - Summary of Amortized Cost Basis of Modifications to Borrowers Experiencing Financial Difficulty (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2025	Mar. 31, 2024
Financing Receivable, Allowance for Credit Losses
Amortized cost basis of the modifications to borrowers experiencing financial difficulty	$ 54	$ 23
Term Extension
Financing Receivable, Allowance for Credit Losses
Amortized cost basis of the modifications to borrowers experiencing financial difficulty	0	8
Interest Rate Reduction
Financing Receivable, Allowance for Credit Losses
Amortized cost basis of the modifications to borrowers experiencing financial difficulty	4	4
Payment Delay
Financing Receivable, Allowance for Credit Losses
Amortized cost basis of the modifications to borrowers experiencing financial difficulty	11	1
Term Extension and Interest Rate Reduction
Financing Receivable, Allowance for Credit Losses
Amortized cost basis of the modifications to borrowers experiencing financial difficulty	0	1
Term Extension and Payment Delay
Financing Receivable, Allowance for Credit Losses
Amortized cost basis of the modifications to borrowers experiencing financial difficulty	37	9
Term Extension, Interest Rate Reduction and Payment Delay
Financing Receivable, Allowance for Credit Losses
Amortized cost basis of the modifications to borrowers experiencing financial difficulty	2	0
Commercial | Commercial and industrial loans
Financing Receivable, Allowance for Credit Losses
Amortized cost basis of the modifications to borrowers experiencing financial difficulty	17	9
Commercial | Commercial and industrial loans | Term Extension
Financing Receivable, Allowance for Credit Losses
Amortized cost basis of the modifications to borrowers experiencing financial difficulty	0	8
Commercial | Commercial and industrial loans | Interest Rate Reduction
Financing Receivable, Allowance for Credit Losses
Amortized cost basis of the modifications to borrowers experiencing financial difficulty	0	0
Commercial | Commercial and industrial loans | Payment Delay
Financing Receivable, Allowance for Credit Losses
Amortized cost basis of the modifications to borrowers experiencing financial difficulty	11	0
Commercial | Commercial and industrial loans | Term Extension and Interest Rate Reduction
Financing Receivable, Allowance for Credit Losses
Amortized cost basis of the modifications to borrowers experiencing financial difficulty	0	1
Commercial | Commercial and industrial loans | Term Extension and Payment Delay
Financing Receivable, Allowance for Credit Losses
Amortized cost basis of the modifications to borrowers experiencing financial difficulty	6	0
Commercial | Commercial and industrial loans | Term Extension, Interest Rate Reduction and Payment Delay
Financing Receivable, Allowance for Credit Losses
Amortized cost basis of the modifications to borrowers experiencing financial difficulty	0	0
Commercial | Commercial mortgage owner-occupied loans
Financing Receivable, Allowance for Credit Losses
Amortized cost basis of the modifications to borrowers experiencing financial difficulty	24	0
Commercial | Commercial mortgage owner-occupied loans | Term Extension
Financing Receivable, Allowance for Credit Losses
Amortized cost basis of the modifications to borrowers experiencing financial difficulty	0	0
Commercial | Commercial mortgage owner-occupied loans | Interest Rate Reduction
Financing Receivable, Allowance for Credit Losses
Amortized cost basis of the modifications to borrowers experiencing financial difficulty	0	0
Commercial | Commercial mortgage owner-occupied loans | Payment Delay
Financing Receivable, Allowance for Credit Losses
Amortized cost basis of the modifications to borrowers experiencing financial difficulty	0	0
Commercial | Commercial mortgage owner-occupied loans | Term Extension and Interest Rate Reduction
Financing Receivable, Allowance for Credit Losses
Amortized cost basis of the modifications to borrowers experiencing financial difficulty	0	0
Commercial | Commercial mortgage owner-occupied loans | Term Extension and Payment Delay
Financing Receivable, Allowance for Credit Losses
Amortized cost basis of the modifications to borrowers experiencing financial difficulty	24	0
Commercial | Commercial mortgage owner-occupied loans | Term Extension, Interest Rate Reduction and Payment Delay
Financing Receivable, Allowance for Credit Losses
Amortized cost basis of the modifications to borrowers experiencing financial difficulty	0	0
Residential Mortgage
Financing Receivable, Allowance for Credit Losses
Amortized cost basis of the modifications to borrowers experiencing financial difficulty	9	9
Residential Mortgage | Term Extension
Financing Receivable, Allowance for Credit Losses
Amortized cost basis of the modifications to borrowers experiencing financial difficulty	0	0
Residential Mortgage | Interest Rate Reduction
Financing Receivable, Allowance for Credit Losses
Amortized cost basis of the modifications to borrowers experiencing financial difficulty	0	0
Residential Mortgage | Payment Delay
Financing Receivable, Allowance for Credit Losses
Amortized cost basis of the modifications to borrowers experiencing financial difficulty	0	1
Residential Mortgage | Term Extension and Interest Rate Reduction
Financing Receivable, Allowance for Credit Losses
Amortized cost basis of the modifications to borrowers experiencing financial difficulty	0	0
Residential Mortgage | Term Extension and Payment Delay
Financing Receivable, Allowance for Credit Losses
Amortized cost basis of the modifications to borrowers experiencing financial difficulty	7	8
Residential Mortgage | Term Extension, Interest Rate Reduction and Payment Delay
Financing Receivable, Allowance for Credit Losses
Amortized cost basis of the modifications to borrowers experiencing financial difficulty	2	0
Consumer | Home equity
Financing Receivable, Allowance for Credit Losses
Amortized cost basis of the modifications to borrowers experiencing financial difficulty	1	1
Consumer | Home equity | Term Extension
Financing Receivable, Allowance for Credit Losses
Amortized cost basis of the modifications to borrowers experiencing financial difficulty	0	0
Consumer | Home equity | Interest Rate Reduction
Financing Receivable, Allowance for Credit Losses
Amortized cost basis of the modifications to borrowers experiencing financial difficulty	1	0
Consumer | Home equity | Payment Delay
Financing Receivable, Allowance for Credit Losses
Amortized cost basis of the modifications to borrowers experiencing financial difficulty	0	0
Consumer | Home equity | Term Extension and Interest Rate Reduction
Financing Receivable, Allowance for Credit Losses
Amortized cost basis of the modifications to borrowers experiencing financial difficulty	0	0
Consumer | Home equity | Term Extension and Payment Delay
Financing Receivable, Allowance for Credit Losses
Amortized cost basis of the modifications to borrowers experiencing financial difficulty	0	1
Consumer | Home equity | Term Extension, Interest Rate Reduction and Payment Delay
Financing Receivable, Allowance for Credit Losses
Amortized cost basis of the modifications to borrowers experiencing financial difficulty	0	0
Consumer | Credit card
Financing Receivable, Allowance for Credit Losses
Amortized cost basis of the modifications to borrowers experiencing financial difficulty	3	4
Consumer | Credit card | Term Extension
Financing Receivable, Allowance for Credit Losses
Amortized cost basis of the modifications to borrowers experiencing financial difficulty	0	0
Consumer | Credit card | Interest Rate Reduction
Financing Receivable, Allowance for Credit Losses
Amortized cost basis of the modifications to borrowers experiencing financial difficulty	3	4
Consumer | Credit card | Payment Delay
Financing Receivable, Allowance for Credit Losses
Amortized cost basis of the modifications to borrowers experiencing financial difficulty	0	0
Consumer | Credit card | Term Extension and Interest Rate Reduction
Financing Receivable, Allowance for Credit Losses
Amortized cost basis of the modifications to borrowers experiencing financial difficulty	0	0
Consumer | Credit card | Term Extension and Payment Delay
Financing Receivable, Allowance for Credit Losses
Amortized cost basis of the modifications to borrowers experiencing financial difficulty	0	0
Consumer | Credit card | Term Extension, Interest Rate Reduction and Payment Delay
Financing Receivable, Allowance for Credit Losses
Amortized cost basis of the modifications to borrowers experiencing financial difficulty	$ 0	$ 0