Reserves for Credit Losses (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Feb. 01, 2020	Jan. 01, 2020
Card Members Receivable Reserve for Credit Losses [Roll Forward]
Balance, January 1	$ 162
Balance, March 31	69
Allowance for Card Member receivables, recoveries of bad debts	24	$ 31
Participation interests in Card Member receivables purchased from affiliates		1,600
Accounting Standards Update 2016-13 [Member]
Card Members Receivable Reserve for Credit Losses [Roll Forward]
Balance, January 1	15	167
Provisions	100	60
Net write-offs	(50)	(61)
Other adjustments	4	9
Balance, March 31	69	$ 175
Decrease related to adoption of the CECL methodology				$ 147
Card Member Receivables [Member]
Card Members Receivable Reserve for Credit Losses [Roll Forward]
Balance, January 1	162
Balance, March 31	$ 69
Card Member Receivables [Member] | Global Consumer Services Group [Member]
Card Members Receivable Reserve for Credit Losses [Roll Forward]
Removal of Card Member receivables			$ 7,200