Debt - Schedule of Debt (Details) - USD ($)	Dec. 31, 2019	Dec. 31, 2018
SHORT-TERM DEBT
Short-term debt	$ 504,000,000	$ 66,000,000
LONG-TERM DEBT
Senior notes, net of unamortized discounts and debt issuance costs	8,939,000,000	8,941,000,000
Noncurrent portion of other long-term debt	248,000,000	202,000,000
Total long-term debt	9,187,000,000	9,143,000,000
Total debt	9,691,000,000	9,209,000,000
Other
SHORT-TERM DEBT
Short-term debt	86,000,000	66,000,000
Commercial Paper \| Line of Credit
SHORT-TERM DEBT
Short-term notes and borrowings	$ 93,000,000
Weighted average interest rate, short-term (as a percent)	2.20%
Senior secured hedged inventory facility \| Line of Credit
SHORT-TERM DEBT
Short-term notes and borrowings	$ 325,000,000
Weighted average interest rate, short-term (as a percent)	2.70%
Senior notes
LONG-TERM DEBT
Unamortized discounts and debt issuance costs	$ (61,000,000)	(59,000,000)
Senior notes, net of unamortized discounts and debt issuance costs	8,939,000,000	8,941,000,000
Debt instrument face value	9,000,000,000.0	9,000,000,000.0
Senior notes \| Level 2
LONG-TERM DEBT
Debt instrument fair value	$ 9,300,000,000	8,600,000,000
Senior notes \| 2.60% senior notes due December 2019
LONG-TERM DEBT
Long-term debt, before deducting unamortized discounts and debt issuance costs		$ 500,000,000
Debt instrument, interest rate (as a percent)	2.60%	2.60%
Debt instrument face value		$ 500,000,000
Senior notes \| 5.75% senior notes due January 2020
LONG-TERM DEBT
Long-term debt, before deducting unamortized discounts and debt issuance costs		$ 500,000,000
Debt instrument, interest rate (as a percent)	5.75%	5.75%
Senior notes \| 5.00% senior notes due February 2021
LONG-TERM DEBT
Long-term debt, before deducting unamortized discounts and debt issuance costs	$ 600,000,000	$ 600,000,000
Debt instrument, interest rate (as a percent)	5.00%	5.00%
Senior notes \| 3.65% senior notes due June 2022
LONG-TERM DEBT
Long-term debt, before deducting unamortized discounts and debt issuance costs	$ 750,000,000	$ 750,000,000
Debt instrument, interest rate (as a percent)	3.65%	3.65%
Senior notes \| 2.85% senior notes due January 2023
LONG-TERM DEBT
Long-term debt, before deducting unamortized discounts and debt issuance costs	$ 400,000,000	$ 400,000,000
Debt instrument, interest rate (as a percent)	2.85%	2.85%
Senior notes \| 3.85% senior notes due October 2023
LONG-TERM DEBT
Long-term debt, before deducting unamortized discounts and debt issuance costs	$ 700,000,000	$ 700,000,000
Debt instrument, interest rate (as a percent)	3.85%	3.85%
Senior notes \| 3.60% senior notes due November 2024
LONG-TERM DEBT
Long-term debt, before deducting unamortized discounts and debt issuance costs	$ 750,000,000	$ 750,000,000
Debt instrument, interest rate (as a percent)	3.60%	3.60%
Senior notes \| 4.65% senior notes due October 2025
LONG-TERM DEBT
Long-term debt, before deducting unamortized discounts and debt issuance costs	$ 1,000,000,000	$ 1,000,000,000
Debt instrument, interest rate (as a percent)	4.65%	4.65%
Senior notes \| 4.50% senior notes due December 2026
LONG-TERM DEBT
Long-term debt, before deducting unamortized discounts and debt issuance costs	$ 750,000,000	$ 750,000,000
Debt instrument, interest rate (as a percent)	4.50%	4.50%
Senior notes \| 3.55% senior notes due December 2029
LONG-TERM DEBT
Long-term debt, before deducting unamortized discounts and debt issuance costs	$ 1,000,000,000
Debt instrument, interest rate (as a percent)	3.55%
Debt instrument face value	$ 1,000,000,000
Senior notes \| 6.70% senior notes due May 2036
LONG-TERM DEBT
Long-term debt, before deducting unamortized discounts and debt issuance costs	$ 250,000,000	$ 250,000,000
Debt instrument, interest rate (as a percent)	6.70%	6.70%
Senior notes \| 6.65% senior notes due January 2037
LONG-TERM DEBT
Long-term debt, before deducting unamortized discounts and debt issuance costs	$ 600,000,000	$ 600,000,000
Debt instrument, interest rate (as a percent)	6.65%	6.65%
Senior notes \| 5.15% senior notes due June 2042
LONG-TERM DEBT
Long-term debt, before deducting unamortized discounts and debt issuance costs	$ 500,000,000	$ 500,000,000
Debt instrument, interest rate (as a percent)	5.15%	5.15%
Senior notes \| 4.30% senior notes due January 2043
LONG-TERM DEBT
Long-term debt, before deducting unamortized discounts and debt issuance costs	$ 350,000,000	$ 350,000,000
Debt instrument, interest rate (as a percent)	4.30%	4.30%
Senior notes \| 4.70% senior notes due June 2044
LONG-TERM DEBT
Long-term debt, before deducting unamortized discounts and debt issuance costs	$ 700,000,000	$ 700,000,000
Debt instrument, interest rate (as a percent)	4.70%	4.70%
Senior notes \| 4.90% senior notes due February 2045
LONG-TERM DEBT
Long-term debt, before deducting unamortized discounts and debt issuance costs	$ 650,000,000	$ 650,000,000
Debt instrument, interest rate (as a percent)	4.90%	4.90%
Term Loan \| GO Zone Term Loans
LONG-TERM DEBT
Noncurrent portion of other long-term debt	$ 199,000,000	$ 198,000,000
Debt issuance costs	$ 1,000,000	$ 2,000,000
Weighted average long term debt interest rate	2.60%	3.10%
Other long-term debt
LONG-TERM DEBT
Noncurrent portion of other long-term debt	$ 49,000,000	$ 4,000,000

Amount of short-term and long-term debt and lease obligation.

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