Pension and Other Postretirement Employee Benefit Plans - Net Periodic Benefit Costs and Fair Value of Plan Assets (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Retirement Benefits [Abstract]
Total net periodic defined benefit plan cost/(credit)	$ (75)	$ (60)	$ (139)	$ (119)
Total defined contribution plans	357	350	701	671
Total pension and OPEB cost included in noninterest expense	$ 282	$ 290	$ 562	$ 552