Loans and Card Member Receivables (Details 4) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Impaired loans and receivables
Loans over 90 days past due and accruing interest	$ 226	$ 428	$ 387
Non-accrual loans	176	338	279
Loans and receivables modified as a Troubled Debt Restructuring in Program	3,086	762	462
Loans and receivables modified as Troubled Debt Restructuring Out of Program	430	259	198
Total impaired loans and receivables	3,918	1,787	1,326
Reserve for Credit Losses - TDRs	1,346	168	101
Accounts Receivable and Loans (Textuals) [Abstract]
Total loans and receivables modified as a TDR, past due 90 days and still accruing	32	26	17
Total loans and receivables modified as a TDR, non-accrual	11	10	6
Out of Program TDR accounts that completed modification programs	316	188	148
Out of Program TDR accounts not in compliance with modification programs	114	72	50
Other Loans [Member]
Impaired loans and receivables
Loans over 90 days past due and accruing interest	2
Non-accrual loans	1
Loans and receivables modified as a Troubled Debt Restructuring in Program	248
Loans and receivables modified as Troubled Debt Restructuring Out of Program	6
Total impaired loans and receivables	257
Reserve for Credit Losses - TDRs	80
Global Consumer Services Group [Member] | Card Member Loans [Member]
Impaired loans and receivables
Loans over 90 days past due and accruing interest	203	384	344
Non-accrual loans	146	284	236
Loans and receivables modified as a Troubled Debt Restructuring in Program	1,586	500	313
Loans and receivables modified as Troubled Debt Restructuring Out of Program	248	175	131
Total impaired loans and receivables	2,183	1,343	1,024
Reserve for Credit Losses - TDRs	782	137	80
Global Consumer Services Group [Member] | Card Member Receivables [Member]
Impaired loans and receivables
Loans over 90 days past due and accruing interest	0	0	0
Non-accrual loans	0	0	0
Loans and receivables modified as a Troubled Debt Restructuring in Program	240	56	29
Loans and receivables modified as Troubled Debt Restructuring Out of Program	34	16	13
Total impaired loans and receivables	274	72	42
Reserve for Credit Losses - TDRs	60	3	2
Global Commercial Services [Member] | Card Member Loans [Member]
Impaired loans and receivables
Loans over 90 days past due and accruing interest	21	44	43
Non-accrual loans	29	54	43
Loans and receivables modified as a Troubled Debt Restructuring in Program	478	97	59
Loans and receivables modified as Troubled Debt Restructuring Out of Program	67	38	29
Total impaired loans and receivables	595	233	174
Reserve for Credit Losses - TDRs	285	22	14
Global Commercial Services [Member] | Card Member Receivables [Member]
Impaired loans and receivables
Loans over 90 days past due and accruing interest	0	0	0
Non-accrual loans	0	0	0
Loans and receivables modified as a Troubled Debt Restructuring in Program	534	109	61
Loans and receivables modified as Troubled Debt Restructuring Out of Program	75	30	25
Total impaired loans and receivables	609	139	86
Reserve for Credit Losses - TDRs	$ 139	$ 6	$ 5