Loans and Accounts Receivable (Details 4) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Impaired loans and receivables
Loans over 90 days past due and accruing interest	$ 428	$ 387	$ 327
Non-accrual loans	338	279	199
Loans and receivables modified as a Troubled Debt Restructuring in Program	762	462	261
Loans and receivables modified as Troubled Debt Restructuring Out of Program	259	198	186
Total impaired loans and receivables	1,787	1,326	973
Unpaid principal balance	1,629	1,212	892
Related allowance for Troubled Debt Restructurings	168	101	60
Accounts Receivable and Loans (Textuals) [Abstract]
Total loans and receivables modified as a TDR, past due 90 days and still accruing	26	17	15
Total loans and receivables modified as a TDR, non-accrual	10	6	5
Out of Program TDR accounts that completed modification programs	188	148	141
Out of Program TDR accounts not in compliance with modification programs	72	50	45
Global Consumer Services Group [Member] | Card Member Loans [Member]
Impaired loans and receivables
Loans over 90 days past due and accruing interest	384	344	289
Non-accrual loans	284	236	168
Loans and receivables modified as a Troubled Debt Restructuring in Program	500	313	178
Loans and receivables modified as Troubled Debt Restructuring Out of Program	175	131	131
Total impaired loans and receivables	1,343	1,024	766
Unpaid principal balance	1,199	923	694
Related allowance for Troubled Debt Restructurings	137	80	49
Global Consumer Services Group [Member] | Card Member Loans [Member] | Outside the United States [Member]
Impaired loans and receivables
Loans over 90 days past due and accruing interest	93	69	56
Unpaid principal balance	77	68	55
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	56	29	15
Loans and receivables modified as Troubled Debt Restructuring Out of Program	16	13	9
Total impaired loans and receivables	72	42	24
Unpaid principal balance	72	42	24
Related allowance for Troubled Debt Restructurings	3	2	1
Global Commercial Services [Member] | Card Member Loans [Member]
Impaired loans and receivables
Loans over 90 days past due and accruing interest	44	43	38
Non-accrual loans	54	43	31
Loans and receivables modified as a Troubled Debt Restructuring in Program	97	59	31
Loans and receivables modified as Troubled Debt Restructuring Out of Program	38	29	27
Total impaired loans and receivables	233	174	127
Unpaid principal balance	220	161	118
Related allowance for Troubled Debt Restructurings	22	14	8
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	109	61	37
Loans and receivables modified as Troubled Debt Restructuring Out of Program	30	25	19
Total impaired loans and receivables	139	86	56
Unpaid principal balance	138	86	56
Related allowance for Troubled Debt Restructurings	$ 6	$ 5	$ 2