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, 2024	Mar. 31, 2023
Financing Receivable, Allowance for Credit Losses
Amortized cost basis of the modifications to borrowers experiencing financial difficulty	$ 23	$ 0
Term Extension
Financing Receivable, Allowance for Credit Losses
Amortized cost basis of the modifications to borrowers experiencing financial difficulty	8
Interest Rate Reduction
Financing Receivable, Allowance for Credit Losses
Amortized cost basis of the modifications to borrowers experiencing financial difficulty	4
Payment Delay
Financing Receivable, Allowance for Credit Losses
Amortized cost basis of the modifications to borrowers experiencing financial difficulty	1
Term Extension and Payment Delay
Financing Receivable, Allowance for Credit Losses
Amortized cost basis of the modifications to borrowers experiencing financial difficulty	9
Term Extension and Interest Rate Reduction
Financing Receivable, Allowance for Credit Losses
Amortized cost basis of the modifications to borrowers experiencing financial difficulty	1
Commercial | Commercial and industrial loans
Financing Receivable, Allowance for Credit Losses
Amortized cost basis of the modifications to borrowers experiencing financial difficulty	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	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
Commercial | Commercial and industrial loans | Payment Delay
Financing Receivable, Allowance for Credit Losses
Amortized cost basis of the modifications to borrowers experiencing financial difficulty	0
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	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	1
Residential Mortgage
Financing Receivable, Allowance for Credit Losses
Amortized cost basis of the modifications to borrowers experiencing financial difficulty	9
Residential Mortgage | Term Extension
Financing Receivable, Allowance for Credit Losses
Amortized cost basis of the modifications to borrowers experiencing financial difficulty	0
Residential Mortgage | Interest Rate Reduction
Financing Receivable, Allowance for Credit Losses
Amortized cost basis of the modifications to borrowers experiencing financial difficulty	0
Residential Mortgage | Payment Delay
Financing Receivable, Allowance for Credit Losses
Amortized cost basis of the modifications to borrowers experiencing financial difficulty	1
Residential Mortgage | Term Extension and Payment Delay
Financing Receivable, Allowance for Credit Losses
Amortized cost basis of the modifications to borrowers experiencing financial difficulty	8
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
Consumer | Home equity
Financing Receivable, Allowance for Credit Losses
Amortized cost basis of the modifications to borrowers experiencing financial difficulty	1
Consumer | Home equity | Term Extension
Financing Receivable, Allowance for Credit Losses
Amortized cost basis of the modifications to borrowers experiencing financial difficulty	0
Consumer | Home equity | Interest Rate Reduction
Financing Receivable, Allowance for Credit Losses
Amortized cost basis of the modifications to borrowers experiencing financial difficulty	0
Consumer | Home equity | Payment Delay
Financing Receivable, Allowance for Credit Losses
Amortized cost basis of the modifications to borrowers experiencing financial difficulty	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	1
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
Consumer | Credit card
Financing Receivable, Allowance for Credit Losses
Amortized cost basis of the modifications to borrowers experiencing financial difficulty	4
Consumer | Credit card | Term Extension
Financing Receivable, Allowance for Credit Losses
Amortized cost basis of the modifications to borrowers experiencing financial difficulty	0
Consumer | Credit card | Interest Rate Reduction
Financing Receivable, Allowance for Credit Losses
Amortized cost basis of the modifications to borrowers experiencing financial difficulty	4
Consumer | Credit card | Payment Delay
Financing Receivable, Allowance for Credit Losses
Amortized cost basis of the modifications to borrowers experiencing financial difficulty	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
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