Reserves for Losses (Details 2) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Accounts Receivable Reserve Roll Forward [line Items]
Balance, January 1	$ 521	$ 467	$ 462
Provision For Doubtful Accounts	937	795	696
Other	(26)	(5)	(17)
Balance, December 31	573	521	467
Principal Write-Offs [Member]
Accounts Receivable Reserve Roll Forward [line Items]
Card Member loans reserves for losses - other	$ (859)	$ (736)	$ (674)