Fair Values - Not Measured at Fair Value on a Recurring Basis (Details) - USD ($) $ in Millions	Sep. 30, 2023	Dec. 31, 2022
Card Member Receivables
Fair Values (Textuals)
Financing receivables, gross	$ 58,825	$ 57,613
Card Member Loans
Fair Values (Textuals)
Financing receivables, gross	117,978	107,964
Variable Interest Entity, Primary Beneficiary | Card Member Receivables
Fair Values (Textuals)
Financing receivables, gross	5,382	5,193
Variable Interest Entity, Primary Beneficiary | Card Member Loans
Fair Values (Textuals)
Financing receivables, gross	27,215	28,461
Carrying Value
Financial assets for which carrying values equal or approximate fair value
Cash and cash equivalents	44,000	34,000
Other financial assets	63,000	60,000
Financial assets carried at other than fair value
Card Member and Other loans, less reserves	120,000	110,000
Financial Liabilities:
Financial liabilities for which carrying values equal or approximate fair value	136,000	123,000
Financial liabilities carried at other than fair value
Certificates of deposit	18,000	16,000
Long-term debt	46,000	43,000
Fair Values (Textuals)
Long-term debt	46,000	43,000
Corresponding Fair Value Amount
Financial assets for which carrying values equal or approximate fair value
Cash and cash equivalents	44,000	34,000
Other financial assets	63,000	60,000
Financial Liabilities:
Financial liabilities for which carrying values equal or approximate fair value	136,000	123,000
Corresponding Fair Value Amount | Variable Interest Entity, Primary Beneficiary | Card Member Receivables
Fair Values (Textuals)
Financing receivables, gross	5,400	5,200
Corresponding Fair Value Amount | Level 1
Financial assets for which carrying values equal or approximate fair value
Cash and cash equivalents	42,000	32,000
Other financial assets	0	0
Financial Liabilities:
Financial liabilities for which carrying values equal or approximate fair value	0	0
Corresponding Fair Value Amount | Level 2
Financial assets for which carrying values equal or approximate fair value
Cash and cash equivalents	2,000	2,000
Other financial assets	63,000	60,000
Financial Liabilities:
Financial liabilities for which carrying values equal or approximate fair value	136,000	123,000
Corresponding Fair Value Amount | Level 3
Financial assets for which carrying values equal or approximate fair value
Cash and cash equivalents	0	0
Other financial assets	0	0
Financial Liabilities:
Financial liabilities for which carrying values equal or approximate fair value	0	0
Portion at Other than Fair Value Measurement
Financial assets carried at other than fair value
Card Member and Other loans, less reserves	124,000	113,000
Financial liabilities carried at other than fair value
Certificates of deposit	18,000	16,000
Long-term debt	45,000	42,000
Fair Values (Textuals)
Long-term debt	45,000	42,000
Portion at Other than Fair Value Measurement | Variable Interest Entity, Primary Beneficiary
Financial liabilities carried at other than fair value
Long-term debt	13,000	12,300
Fair Values (Textuals)
Long-term debt	13,000	12,300
Portion at Other than Fair Value Measurement | Variable Interest Entity, Primary Beneficiary | Card Member Loans
Fair Values (Textuals)
Financing receivables, gross	27,200	28,400
Portion at Other than Fair Value Measurement | Level 1
Financial assets carried at other than fair value
Card Member and Other loans, less reserves	0	0
Financial liabilities carried at other than fair value
Certificates of deposit	0	0
Long-term debt	0	0
Fair Values (Textuals)
Long-term debt	0	0
Portion at Other than Fair Value Measurement | Level 2
Financial assets carried at other than fair value
Card Member and Other loans, less reserves	0	0
Financial liabilities carried at other than fair value
Certificates of deposit	18,000	16,000
Long-term debt	45,000	42,000
Fair Values (Textuals)
Long-term debt	45,000	42,000
Portion at Other than Fair Value Measurement | Level 3
Financial assets carried at other than fair value
Card Member and Other loans, less reserves	124,000	113,000
Financial liabilities carried at other than fair value
Certificates of deposit	0	0
Long-term debt	0	0
Fair Values (Textuals)
Long-term debt	$ 0	$ 0