Debt (Details) (USD $)	3 Months Ended		12 Months Ended
	Mar. 31, 2014		Dec. 31, 2013
Debt Instrument [Line Items]
Debt	$ 5,285,000,000		$ 4,843,000,000
Unamortized Discount	(19,000,000)		(19,000,000)
Total Debt, Net of Discount	5,266,000,000		4,824,000,000
Current Portion of Long Term Debt, net of discount	(200,000,000)	[1]	(200,000,000)	[1]
Long-term Debt Due After One Year	5,011,000,000		4,566,000,000
Credit Facility due October 3, 2018 [Member]
Debt Instrument [Line Items]
Debt	450,000,000		0
Interest Rate (percentage in hundredths)	1.43%		0.00%
Debt instrument, maturity date	Oct. 03, 2018		Oct. 03, 2018
Revolving Credit Facility Maximum Borrowing Capacity	4,000,000,000
Credit facility fee rate basis points, minimum	1250.00%
Credit facility fee rate basis points, maximum	3000.00%
Credit facility aggregate short-term loans and letters of credit, maximum	500,000,000
Credit facility interest rate, Eurodollar rate plus, minimum	10000.00%
Credit facility interest rate, Eurodollar rate plus, maximum	14500.00%
Capital Lease and Other Obligations
Debt Instrument [Line Items]
Debt	351,000,000		359,000,000
Interest Rate (percentage in hundredths)	0.00%		0.00%
FPSO and Other Capital Lease Obligations, Current, net of discount	(55,000,000)		(58,000,000)
5¼% Senior Notes, due April 15, 2014 (1)
Debt Instrument [Line Items]
Debt	200,000,000	[2]	200,000,000
Interest Rate (percentage in hundredths)	5.25%	[2]	5.25%
Debt instrument, maturity date	Apr. 15, 2014		Apr. 15, 2014
Current Portion of Long Term Debt, net of discount	(200,000,000)		(200,000,000)
8¼% Senior Notes, due March 1, 2019
Debt Instrument [Line Items]
Debt	1,000,000,000		1,000,000,000
Interest Rate (percentage in hundredths)	8.25%		8.25%
Debt instrument, maturity date	Mar. 01, 2019		Mar. 01, 2019
4.15% Senior Notes, due December 15, 2021
Debt Instrument [Line Items]
Debt	1,000,000,000		1,000,000,000
Interest Rate (percentage in hundredths)	4.15%		4.15%
Debt instrument, maturity date	Dec. 15, 2021		Dec. 15, 2021
7¼% Senior Notes, due October 15, 2023
Debt Instrument [Line Items]
Debt	100,000,000		100,000,000
Interest Rate (percentage in hundredths)	7.25%		7.25%
Debt instrument, maturity date	Oct. 15, 2023		Oct. 15, 2023
8% Senior Notes, due April 1, 2027
Debt Instrument [Line Items]
Debt	250,000,000		250,000,000
Interest Rate (percentage in hundredths)	8.00%		8.00%
Debt instrument, maturity date	Apr. 01, 2027		Apr. 01, 2027
6% Senior Notes, due March 1, 2041
Debt Instrument [Line Items]
Debt	850,000,000		850,000,000
Interest Rate (percentage in hundredths)	6.00%		6.00%
Debt instrument, maturity date	Mar. 01, 2041		Mar. 01, 2041
5¼% Senior Notes, due November 15, 2043
Debt Instrument [Line Items]
Debt	1,000,000,000		1,000,000,000
Interest Rate (percentage in hundredths)	5.25%		5.25%
Debt instrument, maturity date	Nov. 15, 2043		Nov. 15, 2043
7¼% Senior Debentures, due August 1, 2097
Debt Instrument [Line Items]
Debt	$ 84,000,000		$ 84,000,000
Interest Rate (percentage in hundredths)	7.25%		7.25%
Debt instrument, maturity date	Aug. 01, 2097		Aug. 01, 2097

[1] See Note 6. Debt.

[2] We repaid the Senior Notes on their due date.