Reserves for Losses (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Changes in the Card Member loans reserve for losses [Line Items]
Balance, January 1			$ 2,134	$ 1,706
Provisions	$ 603	$ 528	1,128	1,027
Net write-offs Principal, interest and fees			(254)	(217)
Other			12	2
Ending Balance	$ 2,168	$ 1,840	2,168	1,840
Net Write Offs [Member]
Changes in the Card Member loans reserve for losses [Line Items]
Provisions			1,128	1,027
Provisions for loans and lease losses deductions net write offs principal
Changes in the Card Member loans reserve for losses [Line Items]
Net write-offs Principal, interest and fees			(920)	(747)
Provisions for loans and lease losses deductions net write offs interest and fees
Changes in the Card Member loans reserve for losses [Line Items]
Net write-offs Principal, interest and fees			(186)	(148)
Troubled Debt Restructuring [Member]
Changes in the Card Member loans reserve for losses [Line Items]
Net write-offs Principal, interest and fees			(33)	(14)
Foreign Currency Translation Adjustments [Member]
Changes in the Card Member loans reserve for losses [Line Items]
Other			3	(5)
Other Items [Member]
Changes in the Card Member loans reserve for losses [Line Items]
Other			$ 9	$ 7