Pension and Other Postretirement Employee Benefit Plans - Net Periodic Benefit Costs and Fair Value of Plan Assets (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Retirement Benefits [Abstract]
Total net periodic defined benefit plan cost/(credit)	$ (94)	$ (64)
Total defined contribution plans	365	344
Total pension and OPEB cost included in noninterest expense	$ 271	$ 280