Loans and Card Member Receivables (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Card Member Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivables, gross	$ 73,373	$ 87,381
Financing receivables, reserves for credit losses	5,344	2,383	$ 2,134	$ 1,706
Financing receivables, net	68,029	84,998
Other Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivables, reserves for credit losses	238	152
Financing receivables, net	2,614	4,626
Other Loans [Member] | PPP Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivables, gross	600
Variable Interest Entity, Primary Beneficiary [Member] | Card Member Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivables, gross	25,908	32,230
Global Consumer Services Group [Member] | Card Member Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivables, gross	60,084	73,266
Global Commercial Services [Member] | Card Member Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivables, gross	$ 13,289	$ 14,115