Noninterest Revenue and Noninterest Expense - Card Income (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Disaggregation of Revenue [Line Items]
Total card income	$ 975	$ 1,350
Interchange and merchant processing income
Disaggregation of Revenue [Line Items]
Total card income	6,235	4,868
Rewards costs and partner payments
Disaggregation of Revenue [Line Items]
Total card income	(4,870)	(3,534)
Other card income
Disaggregation of Revenue [Line Items]
Total card income	$ (390)	$ 16