Reserves for Credit Losses (Details 1) - 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 Loans
Reserve for Losses [Roll Forward]
Beginning Balance	4,467	5,236	5,344	4,027
Provisions	(396)	969	(969)	2,845
Other	7	25	7	(17)
Ending Balance	3,835	5,628	3,835	5,628
Net (write-offs) recoveries from TDRs	(43)	(32)	(88)	(63)
Foreign currency translation adjustments	7	25	6	(17)
Card Member Loans | Principal
Reserve for Losses [Roll Forward]
Net write-offs	(185)	(499)	(426)	(1,017)
Recoveries	172	134	340	279
Card Member Loans | Interest and fees
Reserve for Losses [Roll Forward]
Net write-offs	$ (58)	$ (103)	$ (121)	$ (210)