Reserves for Credit Losses (Details 2) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Provisions	$ 29	$ (12)	$ (9)	$ 264
Card Member Receivables
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recoveries	14	21	52	59
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Balance	(4)	184	70	15
Provisions	25	(16)	(21)	248
Net write-offs	(11)	(59)	(39)	(160)
Other adjustments	0	1	0	7
Ending Balance	$ 10	110	$ 10	110
Card Member Receivables | Global Consumer Services Group
Accounts, Notes, Loans and Financing Receivable [Line Items]
Removal of financing receivables		$ 7,200		$ 7,200