Reserves for Credit Losses (Details 1) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Reserve for Losses [Roll Forward]
Provisions	$ (675)	$ 2,621
Card Member Loans
Reserve for Losses [Roll Forward]
Beginning Balance	5,344	4,027
Provisions	(573)	1,876
Other	0	(42)
Ending Balance	4,467	5,236
Net (write-offs) recoveries from TDRs	(45)	(31)
Foreign currency translation adjustments	(1)	(42)
Card Member Loans | Principal
Reserve for Losses [Roll Forward]
Net write-offs	(241)	(518)
Recoveries	168	145
Card Member Loans | Interest and fees
Reserve for Losses [Roll Forward]
Net write-offs	$ (63)	$ (107)