Reserves for Credit Losses (Details 2) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Provisions	$ (24)	$ 173	$ (38)	$ 276
Card Member Receivables
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recoveries	17	15	38	38
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Balance	30	69	70	15
Provisions	(24)	164	(46)	264
Net write-offs	(10)	(51)	(28)	(101)
Other adjustments	0	2	0	6
Ending Balance	$ (4)	184	$ (4)	184
Card Member Receivables | Global Consumer Services Group
Accounts, Notes, Loans and Financing Receivable [Line Items]
Removal of financing receivables		$ 7,200		$ 7,200