Fair Value 1 (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Financial assets carried at other than fair value
Loans to affiliates and other	$ 10,890	$ 10,345	$ 14,136
Financial liabilities carried at other than fair value
Long-term debt	7,037	13,469
Long-term debt with affiliates	822	9,292	$ 7,523
Card Member Loans [Member]
Financial assets carried at other than fair value
Card Member loans, less reserves for credit losses	480	687
Carrying Value [Member]
Financial assets for which carrying values equal or approximate fair value
Cash and cash equivalents per Consolidated Balance Sheets	600	100
Other financial assets	12,100	26,200
Financial assets carried at other than fair value
Loans to affiliates and other	10,900	10,300
Financial Liabilities:
Financial liabilities for which carrying values equal or approximate fair value	12,600	11,200
Financial liabilities carried at other than fair value
Long-term debt	7,000	13,500
Long-term debt with affiliates	800	9,300
Carrying Value [Member] | Card Member Loans [Member]
Financial assets carried at other than fair value
Card Member loans, less reserves for credit losses	500	700
Estimate of Fair Value Measurement [Member]
Financial assets for which carrying values equal or approximate fair value
Cash and cash equivalents per Consolidated Balance Sheets	600	100
Other financial assets	12,100	26,200
Financial assets carried at other than fair value
Loans to affiliates and other	11,100	10,400
Financial Liabilities:
Financial liabilities for which carrying values equal or approximate fair value	12,600	11,200
Financial liabilities carried at other than fair value
Long-term debt	7,400	13,700
Long-term debt with affiliates	800	9,400
Estimate of Fair Value Measurement [Member] | Card Member Loans [Member]
Financial assets carried at other than fair value
Card Member loans, less reserves for credit losses	500	700
Estimate of Fair Value Measurement [Member] | Level 1 [Member]
Financial assets for which carrying values equal or approximate fair value
Cash and cash equivalents per Consolidated Balance Sheets	600	100
Other financial assets	0	0
Financial assets carried at other than fair value
Loans to affiliates and other	0	0
Financial Liabilities:
Financial liabilities for which carrying values equal or approximate fair value	0	0
Financial liabilities carried at other than fair value
Long-term debt	0	0
Long-term debt with affiliates	0	0
Estimate of Fair Value Measurement [Member] | Level 1 [Member] | Card Member Loans [Member]
Financial assets carried at other than fair value
Card Member loans, less reserves for credit losses	0	0
Estimate of Fair Value Measurement [Member] | Level 2 [Member]
Financial assets for which carrying values equal or approximate fair value
Cash and cash equivalents per Consolidated Balance Sheets	0	0
Other financial assets	12,100	26,200
Financial assets carried at other than fair value
Loans to affiliates and other	5,000	2,800
Financial Liabilities:
Financial liabilities for which carrying values equal or approximate fair value	12,600	11,200
Financial liabilities carried at other than fair value
Long-term debt	7,400	13,700
Long-term debt with affiliates	800	9,400
Estimate of Fair Value Measurement [Member] | Level 2 [Member] | Card Member Loans [Member]
Financial assets carried at other than fair value
Card Member loans, less reserves for credit losses	0	0
Estimate of Fair Value Measurement [Member] | Level 3 [Member]
Financial assets for which carrying values equal or approximate fair value
Cash and cash equivalents per Consolidated Balance Sheets	0	0
Other financial assets	0	0
Financial assets carried at other than fair value
Loans to affiliates and other	6,100	7,600
Financial Liabilities:
Financial liabilities for which carrying values equal or approximate fair value	0	0
Financial liabilities carried at other than fair value
Long-term debt	0	0
Long-term debt with affiliates	0	0
Estimate of Fair Value Measurement [Member] | Level 3 [Member] | Card Member Loans [Member]
Financial assets carried at other than fair value
Card Member loans, less reserves for credit losses	$ 500	$ 700