Sum of the carrying values as of the balance sheet date of all debt, including all short-term borrowings, long-term debt, and capital lease obligations.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03.13,16)
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Amount of short-term debt and current maturity of long-term debt and capital lease obligations due within one year or the normal operating cycle, if longer.

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Amount, before unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
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-SubTopic 10
-Section S99
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-Subparagraph (SX 210.5-02(22))
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- Definition

Face (par) amount of debt instrument at time of issuance.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
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- Definition

Fair value portion of debt instrument payable, including, but not limited to, notes payable and loans payable.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
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-Subparagraph (a)
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- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

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Amount of unamortized debt discount (premium) and debt issuance costs.

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-Topic 835
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Amount of long-term debt and capital lease obligation due after one year or beyond the normal operating cycle, if longer.

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Amount of long-term debt classified as other, payable after one year or the operating cycle, if longer.

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- Definition

Carrying value as of the balance sheet date of Notes with the highest claim on the assets of the issuer in case of bankruptcy or liquidation (with maturities initially due after one year or beyond the operating cycle if longer), excluding current portion. Senior note holders are paid off in full before any payments are made to junior note holders.

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Carrying value as of the balance sheet date of the portion of long-term notes having the highest claim on the assets of the issuer in case of bankruptcy or liquidation, due within one year or the normal operating cycle, if longer. Senior note holders are paid off in full before any payments are made to debt holders having a lesser priority of repayment.

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Reflects the total carrying amount as of the balance sheet date of debt having initial terms less than one year or the normal operating cycle, if longer.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(19)(a))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
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-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

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Weighted average interest rate of short-term debt outstanding calculated at point in time.

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Debt - Schedule of Debt (Details) - USD ($)	Dec. 31, 2017	Jan. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
SHORT-TERM DEBT
Short-term debt	$ 737,000,000		$ 1,715,000,000
LONG-TERM DEBT
Senior notes, net of unamortized discounts and debt issuance costs	8,933,000,000		9,874,000,000
Noncurrent portion of other long-term debt	250,000,000		250,000,000
Total long-term debt	9,183,000,000		10,124,000,000
Total debt	9,920,000,000		11,839,000,000
Commercial Paper
SHORT-TERM DEBT
Short-term notes and borrowings	$ 0		$ 563,000,000
Weighted average interest rate, short-term (as a percent)	2.40%		1.60%
Other
SHORT-TERM DEBT
Short-term debt	$ 73,000,000		$ 2,000,000
Exchange Traded
SHORT-TERM DEBT
Short-term debt	212,000,000		410,000,000
Senior secured hedged inventory facility \| Line of Credit
SHORT-TERM DEBT
Short-term notes and borrowings	$ 664,000,000		$ 750,000,000
Weighted average interest rate, short-term (as a percent)	2.60%		1.80%
6.13% senior notes due January 2017 \| Senior notes
SHORT-TERM DEBT
Senior notes, current portion	$ 0		$ 400,000,000
Senior notes
LONG-TERM DEBT
Unamortized discounts and debt issuance costs	(67,000,000)		(76,000,000)
Senior notes, net of unamortized discounts and debt issuance costs	8,933,000,000		9,874,000,000
Debt instrument face value	9,000,000,000		10,300,000,000
Senior notes \| Level 2
LONG-TERM DEBT
Debt instrument fair value	9,100,000,000		$ 10,400,000,000
Senior notes \| 6.13% senior notes due January 2017
LONG-TERM DEBT
Debt instrument, interest rate (as a percent)		6.13%	6.13%
Senior notes \| 6.50% senior notes due May 2018
LONG-TERM DEBT
Long-term debt, before deducting unamortized discounts and debt issuance costs	$ 0		$ 600,000,000
Debt instrument, interest rate (as a percent)	6.50%		6.50%
Senior notes \| 8.75% senior notes due May 2019
LONG-TERM DEBT
Long-term debt, before deducting unamortized discounts and debt issuance costs	$ 0		$ 350,000,000
Debt instrument, interest rate (as a percent)	8.75%		8.75%
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		$ 500,000,000
Debt instrument, interest rate (as a percent)	2.60%		2.60%
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		$ 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%	4.65%
Debt instrument face value				$ 1,000,000,000
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%
Debt instrument face value			$ 750,000,000
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%
Commercial Paper \| Senior secured hedged inventory facility
LONG-TERM DEBT
Noncurrent portion of other long-term debt	$ 247,000,000		$ 247,000,000
Other
LONG-TERM DEBT
Noncurrent portion of other long-term debt	$ 3,000,000		$ 3,000,000