Accrued Liabilities (Details) (USD $) In Millions, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013
Accrued Liabilities [Line Items]
Accrued liabilities	$ 827	$ 978
Revenue payable [Member]
Accrued Liabilities [Line Items]
Accrued liabilities	179	175
Accrued capital costs [Member]
Accrued Liabilities [Line Items]
Accrued liabilities	449	458
Accrued lease operating expenses [Member]
Accrued Liabilities [Line Items]
Accrued liabilities	27	71
Employee incentive expense [Member]
Accrued Liabilities [Line Items]
Accrued liabilities	49	64
Accrued interest on debt [Member]
Accrued Liabilities [Line Items]
Accrued liabilities	48	72
Taxes payable [Member]
Accrued Liabilities [Line Items]
Accrued liabilities	28	93
Other accrued liabilities [Member]
Accrued Liabilities [Line Items]
Accrued liabilities	$ 47	$ 45