Loans and Card Member Receivables (Details 3) - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Impaired loans and receivables
Loans over 90 days past due and accruing interest	$ 201	$ 226
Non-accrual loans	149	176
Loans and receivables modified as a Troubled Debt Restructuring in Program	2,856	3,086
Loans and receivables modified as Troubled Debt Restructuring Out of Program	522	430
Total impaired loans and receivables	3,728	3,918
Reserve for Credit Losses - TDRs	1,251	1,346
Accounts Receivable and Loans Textuals
Total loans and receivables modified as a TDR, past due 90 days and still accruing	35	32
Total loans and receivables modified as a TDR, non-accrual	12	11
Out of Program TDR accounts that completed modification programs	395	316
Out of Program TDR accounts not in compliance with modification programs	127	114
Other Loans
Impaired loans and receivables
Loans over 90 days past due and accruing interest	1	2
Non-accrual loans	1	1
Loans and receivables modified as a Troubled Debt Restructuring in Program	196	248
Loans and receivables modified as Troubled Debt Restructuring Out of Program	7	6
Total impaired loans and receivables	205	257
Reserve for Credit Losses - TDRs	65	80
GCSG | Card Member Loans
Impaired loans and receivables
Loans over 90 days past due and accruing interest	183	203
Non-accrual loans	126	146
Loans and receivables modified as a Troubled Debt Restructuring in Program	1,550	1,586
Loans and receivables modified as Troubled Debt Restructuring Out of Program	293	248
Total impaired loans and receivables	2,152	2,183
Reserve for Credit Losses - TDRs	733	782
GCSG | Card Member Receivables
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	219	240
Loans and receivables modified as Troubled Debt Restructuring Out of Program	41	34
Total impaired loans and receivables	260	274
Reserve for Credit Losses - TDRs	64	60
GCS | Card Member Loans
Impaired loans and receivables
Loans over 90 days past due and accruing interest	17	21
Non-accrual loans	22	29
Loans and receivables modified as a Troubled Debt Restructuring in Program	452	478
Loans and receivables modified as Troubled Debt Restructuring Out of Program	84	67
Total impaired loans and receivables	575	595
Reserve for Credit Losses - TDRs	252	285
GCS | Card Member Receivables
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	439	534
Loans and receivables modified as Troubled Debt Restructuring Out of Program	97	75
Total impaired loans and receivables	536	609
Reserve for Credit Losses - TDRs	$ 137	$ 139