Loans and Accounts Receivable (Details 4) - USD ($) $ in Millions	Sep. 30, 2018	Dec. 31, 2017
Impaired loans and receivables
Loans over 90 days past due and accruing interest	$ 341	$ 327
Non-accrual loans	241	199
Loans and receivables modified as a Troubled Debt Restructuring in Program	414	261
Loans and receivables modified as Troubled Debt Restructuring Out of Program	182	186
Total impaired loans and receivables	1,178	973
Unpaid principal balance	1,079	892
Related allowance for Troubled Debt Restructurings	85	60
Accounts Receivable and Loans Textuals [Abstract]
Total loans and receivables modified as a TDR, non-accrual	5	5
Total loans and receivables modified as a TDR, past due 90 days and still accruing	17	15
Out of Program TDR accounts that completed modification programs	138	141
Out of Program TDR accounts not in compliance with modification programs	44	45
Global Consumer Services Group [Member] | Card Member Loans [Member]
Impaired loans and receivables
Loans over 90 days past due and accruing interest	304	289
Non-accrual loans	205	168
Loans and receivables modified as a Troubled Debt Restructuring in Program	279	178
Loans and receivables modified as Troubled Debt Restructuring Out of Program	122	131
Total impaired loans and receivables	910	766
Unpaid principal balance	823	694
Related allowance for Troubled Debt Restructurings	69	49
Global Consumer Services Group [Member] | Card Member Loans [Member] | Non Us [Member]
Impaired loans and receivables
Loans over 90 days past due and accruing interest	65	56
Unpaid principal balance	64	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
Non-accrual loans	0	0
Loans and receivables modified as a Troubled Debt Restructuring in Program	26	15
Loans and receivables modified as Troubled Debt Restructuring Out of Program	11	9
Total impaired loans and receivables	37	24
Unpaid principal balance	36	24
Related allowance for Troubled Debt Restructurings	2	1
Global Commercial Services [Member] | Card Member Loans [Member]
Impaired loans and receivables
Loans over 90 days past due and accruing interest	37	38
Non-accrual loans	36	31
Loans and receivables modified as a Troubled Debt Restructuring in Program	53	31
Loans and receivables modified as Troubled Debt Restructuring Out of Program	26	27
Total impaired loans and receivables	152	127
Unpaid principal balance	142	118
Related allowance for Troubled Debt Restructurings	11	8
Global Commercial Services [Member] | Card Member Receivables [Member]
Impaired loans and receivables
Loans over 90 days past due and accruing interest	0	0
Non-accrual loans	0	0
Loans and receivables modified as a Troubled Debt Restructuring in Program	56	37
Loans and receivables modified as Troubled Debt Restructuring Out of Program	23	19
Total impaired loans and receivables	79	56
Unpaid principal balance	78	56
Related allowance for Troubled Debt Restructurings	$ 3	$ 2