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
Reserve for Losses [Roll Forward]
Provisions	$ (606)	$ 1,555	$ (1,281)	$ 4,176
Card Member Receivables
Reserve for Losses [Roll Forward]
Beginning Balance	202	459	267	126
Provisions	(125)	355	(135)	952
Net write-offs	(4)	(299)	(57)	(557)
Other	0	4	(2)	(2)
Ending Balance	73	519	73	519
Recoveries	127	88	224	180
Net (write-offs) recoveries from TDRs	(16)	(9)	(36)	(16)
Foreign currency translation adjustments	$ 0	$ 4	$ (1)	$ (1)