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
Reserve for Losses [Roll Forward]
Provisions	$ (191)	$ 665	$ (1,472)	$ 4,841
Card Member Receivables
Reserve for Losses [Roll Forward]
Beginning Balance	73	519	267	126
Provisions	(12)	117	(147)	1,069
Net write-offs	(32)	(219)	(89)	(776)
Other	1	5	(1)	3
Ending Balance	30	422	30	422
Recoveries	79	103	303	283
Net (write-offs) recoveries from TDRs	(15)	(15)	(51)	(31)
Foreign currency translation adjustments	$ 0	$ 3	$ (1)	$ 2