Reserves for Losses (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Reserve for Losses [Roll Forward]
Balance, January 1	$ 2,134	$ 1,706	$ 1,223
Card Member loans provisions	2,462	2,266	1,868
Other	17	26	5
Balance, December 31	2,383	2,134	1,706
Provisions for loans and lease losses deductions net write offs principal [Member]
Reserve for Losses [Roll Forward]
Net write-offs	(1,860)	(1,539)	(1,181)
Provisions for loans and lease losses deductions net write offs interest and fees [Member]
Reserve for Losses [Roll Forward]
Net write-offs	(375)	(304)	(227)
Provisions for loans and lease losses other [Member]
Reserve for Losses [Roll Forward]
Other	$ 22	$ 5	$ 23