Reserves for Losses (Details 2) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Accounts Receivable Reserve Roll Forward [line Items]
Balance, January 1	$ 573	$ 521
Provision For Doubtful Accounts	253	242
Card Member receivables net write-offs	(216)	(199)
Other	(2)	1
Ending Balance	$ 608	$ 565