Reserves for Credit Losses (Details) - USD ($) $ in Millions		6 Months Ended
	Jan. 01, 2020	Jun. 30, 2020	Jun. 30, 2019	Feb. 01, 2020
Card Members Receivable Reserve for Credit Losses [Roll Forward]
Balance, January 1	$ 162	$ 162
Balance, June 30		184
Accounting Standards Update [Extensible List]	us-gaap:AccountingStandardsUpdate201613Member
Allowance for Card Member receivables, recoveries of bad debts		38	$ 64
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]
Balance, January 1	$ 15	15	167
Provisions		264	108
Net write-offs		(101)	(111)
Other adjustments		6	8
Balance, June 30		184	$ 172
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	162
Balance, June 30		$ 184
Card Member Receivables [Member] | Cumulative Effect, Period of Adoption, Adjustment [Member]
Card Members Receivable Reserve for Credit Losses [Roll Forward]
Balance, June 30	$ (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