Long-Term Debt (Details) (USD $)	12 Months Ended
	Dec. 31, 2012		Dec. 31, 2011		Oct. 15, 2011
Debt Instrument [Line Items]
Debt	$ 4,123,000,000		$ 4,495,000,000
Unamortized Discount	(15,000,000)		(26,000,000)
Total Debt, Net of Discount	4,108,000,000		4,469,000,000
Long-Term Debt Due After One Year	3,736,000,000		4,100,000,000
Unamortized Debt Issuance Costs	35,000,000
Repayments of Long-term Debt [Abstract]
2013	328,000,000
2014	200,000,000
2015	0
2016	0
2017	0
Thereafter	3,284,000,000
Total	3,812,000,000
Credit Facility, due October 14, 2016 (1)
Debt Instrument [Line Items]
Debt	0	[1]	0	[1]
Interest Rate	0.00%	[1]	0.00%	[1]
Debt Instrument, Maturity Date	Oct. 14, 2016		Oct. 14, 2016
Unamortized Debt Issuance Costs	4,000,000
Debt Instrument, Offering Date	Sep. 28, 2012
Line of Credit Facility, Maximum Borrowing Capacity	4,000,000,000
Credit facility fee rate basis points, minimum					0.125%
Credit facility fee rate basis points, maximum					0.30%
Old Revolving credit facility borrowing capacity					3,000,000,000
Credit facility interest rate, Eurodollar rate plus, minimum					1.00%
Credit facility interest rate, Eurodollar rate plus, maximum					1.45%
Credit facility aggregate short-term loans and letters of credit, maximum					500,000,000
Credit facility covenant term debt to capitalization ratio maximum					65.00%
CONSOL Installment Payments
Debt Instrument [Line Items]
Debt	328,000,000		656,000,000
Interest Rate	1.79%	[2]	1.76%	[2]
Debt Instrument, Maturity Date Range, Start			Sep. 30, 2012
Debt Instrument, Maturity Date Range, End	Sep. 30, 2013		Sep. 30, 2013
Long-term Debt and Capital Lease Obligations, Current	(324,000,000)		(324,000,000)
Debt Instrument, Offering Date			Sep. 30, 2011
FPSO Lease Obligation
Debt Instrument [Line Items]
Debt	311,000,000		355,000,000
Interest Rate	0.00%		0.00%
Long-term Debt and Capital Lease Obligations, Current	(48,000,000)		(45,000,000)
5¼% Senior Notes, due April 15, 2014
Debt Instrument [Line Items]
Debt	200,000,000		200,000,000
Interest Rate	5.25%		5.25%
Debt Instrument, Maturity Date	Apr. 15, 2014		Apr. 15, 2014
8¼% Senior Notes, due March 1, 2019
Debt Instrument [Line Items]
Debt	1,000,000,000		1,000,000,000
Interest Rate	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	4.15%		4.15%
Debt Instrument, Maturity Date	Dec. 15, 2021		Dec. 15, 2021
Unamortized Debt Issuance Costs	8,000,000
Debt Instrument, Offering Date			Dec. 08, 2011
Debt offerings proceeds, net of discount and underwriting fees	992,000,000
Debt Issuance Proceeds Used To Extinguish Outstanding Debt	400,000,000
7¼% Senior Notes, due October 15, 2023
Debt Instrument [Line Items]
Debt	100,000,000		100,000,000
Interest Rate	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	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	6.00%		6.00%
Debt Instrument, Maturity Date	Mar. 01, 2041		Mar. 01, 2041
Unamortized Debt Issuance Costs	9,000,000
Debt Instrument, Offering Date			Feb. 18, 2011
Debt offerings proceeds, net of discount and underwriting fees	836,000,000
Debt Issuance Proceeds Used To Extinguish Outstanding Debt	470,000,000
7¼% Senior Debentures, due August 1, 2097
Debt Instrument [Line Items]
Debt	84,000,000		84,000,000
Interest Rate	7.25%		7.25%
Debt Instrument, Maturity Date	Aug. 01, 2097		Aug. 01, 2097
CONSOL
Debt Instrument [Line Items]
Installment payment amount for joint venture partnership			$ 328,000,000

[1] Our Credit Agreement provides for a $4.0 billion unsecured revolving Credit Facility. The Credit Facility is available for general corporate purposes.

[2] Imputed rate based on the prevailing market rates for similar debt instruments at the date of assessment.