Reserves for Credit Losses (Details 1) - 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 Loans
Reserve for Losses [Roll Forward]
Beginning Balance	3,835	5,628	5,344	4,027
Provisions	(177)	571	(1,146)	3,416
Other	(8)	12	(1)	(5)
Ending Balance	3,489	5,688	3,489	5,688
Net (write-offs) recoveries from TDRs	(36)	(35)	(124)	(98)
Foreign currency translation adjustments	(8)	13	(2)	(4)
Card Member Loans | Principal
Reserve for Losses [Roll Forward]
Net write-offs	(118)	(432)	(544)	(1,449)
Recoveries	167	142	507	421
Card Member Loans | Interest and fees
Reserve for Losses [Roll Forward]
Net write-offs	$ (43)	$ (91)	$ (164)	$ (301)