Reserves for Credit Losses (Details 1) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
	Jan. 01, 2020	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	$ 619			$ 619
Provisions		$ 117	$ 238	1,069	$ 715
Ending balance		422		422
Decrease in Card Member receivable reserves	$ (619)	(422)		(422)
Accounting Standards Update [Extensible List]	us-gaap:AccountingStandardsUpdate201613Member
Recoveries		103	94	283	278
Cumulative effect of change in accounting principle - Reserve for Credit Losses
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Ending balance	$ (493)
Decrease in Card Member receivable reserves	493
Cumulative effect of change in accounting principle - Reserve for Credit Losses, adjusted balance
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	126	519	616	126	573
Provisions		117	238	1,069	715
Net write-offs		(219)	(231)	(776)	(657)
Other		5	(8)	3	(16)
Ending balance		422	615	422	615
Decrease in Card Member receivable reserves	$ (126)	(422)	(615)	(422)	(615)
Troubled Debt Restructuring [Member]
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Net write-offs		(15)	(5)	(31)	(11)
Foreign Currency Translation Adjustments [Member]
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Other		$ 3	$ (6)	$ 2	$ (3)