Basis of Presentation and Accounting Policies (Details) - USD ($)		3 Months Ended		9 Months Ended
	May 04, 2023	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022	Jun. 30, 2023	Jan. 01, 2023	Dec. 31, 2022	Jun. 30, 2022	Dec. 31, 2021
Business Acquisition [Line Items]
Allowance for loan and lease losses		$ (760,000,000)	$ (664,000,000)	$ (760,000,000)	$ (664,000,000)	$ (737,000,000)		$ (685,000,000)	$ (624,000,000)	$ (670,000,000)
Retained earnings		3,874,000,000		3,874,000,000				3,430,000,000
Accounting Standards Update 2022-02
Business Acquisition [Line Items]
Allowance for loan and lease losses							$ 6,000,000	$ 6,000,000
Retained earnings							$ 4,000,000
TD Transaction
Business Acquisition [Line Items]
Proceeds from merger contract termination	$ 200,000,000
Fee reimbursement received	$ 25,000,000
Merger and integration expense		$ 0	$ 21,000,000	$ 51,000,000	$ 55,000,000