Loans - Credit Card Loan Portfolio, Financial Effects of TDRs and Redefaults (Details) - Credit card - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Financing Receivable, Modified [Line Items]
New enrollments, percent of total retained credit card loans (less than)				1.00%
Balance of new TDRs		$ 111		$ 274
Weighted-average interest rate of loans – before TDR		20.26%		19.19%
Weighted-average interest rate of loans – after TDR		3.81%		4.37%
Balance of loans that redefaulted within one year of modification	$ 18	$ 9	$ 24	$ 26
Number of years before payment default under a modified loan				1 year