Reserves for Credit Losses (Details 2) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Reserve for Losses [Roll Forward]
Provisions	$ (675)	$ 2,621
Card Member Receivables
Reserve for Losses [Roll Forward]
Beginning Balance	267	126
Provisions	(10)	597
Net write-offs	(53)	(258)
Other	(2)	(6)
Ending Balance	202	459
Recoveries	97	92
Net (write-offs) recoveries from TDRs	(20)	(7)
Foreign currency translation adjustments	$ (1)	$ (5)