Reserves for Credit Losses (Details) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
	Jan. 01, 2020	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Feb. 01, 2020
Card Members Receivable Reserve for Credit Losses [Roll Forward]
Beginning Balance	$ 162			$ 162
Ending Balance		$ 110		110
Accounting Standards Update [Extensible List]	us-gaap:AccountingStandardsUpdate201613Member
Allowance for Card Member receivables, recoveries of bad debts		21	$ 30	59	$ 94
Participation interests in Card Member receivables purchased from affiliates					2,700
Participation interests in Card Member receivables sold to affiliate					1,100
Cumulative Effect, Period of Adoption, Adjustment [Member]
Card Members Receivable Reserve for Credit Losses [Roll Forward]
Beginning Balance	$ 15	184	172	15	167
Provisions		(16)	52	248	160
Net write-offs		(59)	(55)	(160)	(166)
Other adjustments		1	(1)	7	7
Ending Balance		110	$ 168	110	$ 168
Decrease related to adoption of the CECL methodology	147
Card Member Receivables [Member]
Card Members Receivable Reserve for Credit Losses [Roll Forward]
Beginning Balance	162			162
Ending Balance		$ 110		$ 110
Card Member Receivables [Member] | Cumulative Effect, Period of Adoption, Adjustment [Member]
Card Members Receivable Reserve for Credit Losses [Roll Forward]
Ending Balance	$ (147)
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