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		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Financing Receivable, Allowance for Credit Losses
Amortized cost basis of the modifications to borrowers experiencing financial difficulty	$ 31	$ 0	$ 52	$ 0
Payment Delay
Financing Receivable, Allowance for Credit Losses
Amortized cost basis of the modifications to borrowers experiencing financial difficulty	13		14
Term Extension and Payment Delay
Financing Receivable, Allowance for Credit Losses
Amortized cost basis of the modifications to borrowers experiencing financial difficulty	13		22
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
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	5		7
Commercial | Commercial and industrial loans
Financing Receivable, Allowance for Credit Losses
Amortized cost basis of the modifications to borrowers experiencing financial difficulty	19		28
Commercial | Commercial and industrial loans | Payment Delay
Financing Receivable, Allowance for Credit Losses
Amortized cost basis of the modifications to borrowers experiencing financial difficulty	13		13
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		6
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
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
Residential Mortgage
Financing Receivable, Allowance for Credit Losses
Amortized cost basis of the modifications to borrowers experiencing financial difficulty	7		17
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 Payment Delay
Financing Receivable, Allowance for Credit Losses
Amortized cost basis of the modifications to borrowers experiencing financial difficulty	7		16
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
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
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 | 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 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
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		1
Consumer | Credit card
Financing Receivable, Allowance for Credit Losses
Amortized cost basis of the modifications to borrowers experiencing financial difficulty	4		6
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 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
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	$ 4		$ 6