Loans and Card Member Receivables (Details 6) account in Thousands, $ in Millions	12 Months Ended
	Dec. 31, 2020 USD ($) account	Dec. 31, 2019 USD ($) account	Dec. 31, 2018 USD ($) account
Financing Receivable, Modifications [Line Items]
Number of Accounts | account	23	16	12
Aggregated outstanding balance upon payment default | $	$ 188	$ 106	$ 57
Card Member Loans [Member]
Financing Receivable, Modifications [Line Items]
Number of Accounts | account	17	12	8
Aggregated outstanding balance upon payment default | $	$ 127	$ 86	$ 46
Card Member Receivables [Member]
Financing Receivable, Modifications [Line Items]
Number of Accounts | account	3	4	4
Aggregated outstanding balance upon payment default | $	$ 55	$ 20	$ 11
Other Loans [Member]
Financing Receivable, Modifications [Line Items]
Number of Accounts | account	3
Aggregated outstanding balance upon payment default | $	$ 6