Pension and Other Postretirement Employee Benefit Plans - Net Periodic Benefit Costs (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Pension and OPEB plans
Total net periodic defined benefit plan cost/(credit)	$ (192)	$ (201)	$ (285)
Total defined contribution plans	1,408	1,333	1,332
Total pension and OPEB cost included in noninterest expense	1,216	1,132	1,047
Total recognized in other comprehensive (income)/loss	1,459	(1,129)	$ (214)
Defined benefit pension plans
Defined Benefit Plan Disclosure [Line Items]
Pension settlement loss	$ 92	$ 33