Loans and Accounts Receivable (Details 4) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Impaired loans and receivables
Loans over 90 days past due and accruing interest	$ 387	$ 327	$ 260
Non-accrual loans	279	199	169
Loans and receivables modified as a Troubled Debt Restructuring in Program	462	261	230
Loans and receivables modified as Troubled Debt Restructuring Out of Program	198	186	171
Total impaired loans and receivables	1,326	973	830
Unpaid principal balance	1,212	892	767
Related allowance for Troubled Debt Restructurings	101	60	88
Accounts Receivable and Loans (Textuals) [Abstract]
Total loans and receivables modified as a TDR, non-accrual	6	5	11
Total loans and receivables modified as a TDR, past due 90 days and still accruing	17	15	20
Out of Program TDR accounts that completed modification programs	148	141	132
Out of Program TDR accounts not in compliance with modification programs	50	45	39
Global Consumer Services Group [Member] | Card Member Loans [Member]
Impaired loans and receivables
Loans over 90 days past due and accruing interest	344	289	230
Non-accrual loans	236	168	139
Loans and receivables modified as a Troubled Debt Restructuring in Program	313	178	165
Loans and receivables modified as Troubled Debt Restructuring Out of Program	131	131	129
Total impaired loans and receivables	1,024	766	663
Unpaid principal balance	923	694	609
Related allowance for Troubled Debt Restructurings	80	49	51
Global Consumer Services Group [Member] | Card Member Loans [Member] | Outside the United States
Impaired loans and receivables
Loans over 90 days past due and accruing interest	69	56	52
Unpaid principal balance	68	55	51
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	29	15	11
Loans and receivables modified as Troubled Debt Restructuring Out of Program	13	9	6
Total impaired loans and receivables	42	24	17
Unpaid principal balance	42	24	17
Related allowance for Troubled Debt Restructurings	2	1	7
Global Commercial Services [Member] | Card Member Loans [Member]
Impaired loans and receivables
Loans over 90 days past due and accruing interest	43	38	30
Non-accrual loans	43	31	30
Loans and receivables modified as a Troubled Debt Restructuring in Program	59	31	26
Loans and receivables modified as Troubled Debt Restructuring Out of Program	29	27	26
Total impaired loans and receivables	174	127	112
Unpaid principal balance	161	118	103
Related allowance for Troubled Debt Restructurings	14	8	9
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	61	37	28
Loans and receivables modified as Troubled Debt Restructuring Out of Program	25	19	10
Total impaired loans and receivables	86	56	38
Unpaid principal balance	86	56	38
Related allowance for Troubled Debt Restructurings	$ 5	$ 2	$ 21