Transactions with Affiliates Textuals (Details) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Related Party Transactions [Abstract]
Card Member receivables and loans purchased without recourse from TRS	$ 316,000,000,000	$ 299,000,000,000	$ 262,000,000,000
Participation interest and card member receivables sold to affiliates	1,100,000,000	6,200,000,000	9,400,000,000
Discount revenue earned from purchased Card Member receivables and Card Member loans	1,204,000,000	1,017,000,000	760,000,000
Participation Interests In Card Member Receivables Purchased	8,100,000,000	6,700,000,000
Uncharged servicing fees to affiliates	328,000,000	305,000,000	234,000,000
Restricted cash with affiliates	116,000,000	93,000,000	100,000,000
Long-term debt with affiliates	9,292,000,000	7,523,000,000	270,000,000
Related Party Transaction [Line Items]
Loss reserves	10,000,000	5,000,000	5,000,000	$ 5,000,000
Loans to affiliates and other	10,345,000,000	14,136,000,000	$ 14,527,000,000
Affiliated Entity [Member]
Related Party Transaction [Line Items]
Loss reserves	0	0
RFC VIII [Member] | Collateralized [Member]
Related Party Transaction [Line Items]
Loans to affiliates and other	$ 8,200,000,000	$ 7,200,000,000