Commitments and Contingencies (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011		Dec. 31, 2010	Dec. 31, 2009
Commitments and Contingencies [Abstract]
Expected CONE MARC payment, 2012	$ 23
Rental expense for office buildings and oil and gas operations equipment	31		27	22
Significant Purchase And Supply Commitments [Line Items]
2012	1,152
2013	241
2014	158
2015	139
2016	100
2017 and Thereafter	454
Total	2,244
Drilling, Equipment, and Purchase Obligations [Member]
Significant Purchase And Supply Commitments [Line Items]
2012	980
2013	93
2014	21
2015	13
2016	0
2017 and Thereafter	0
Total	1,107
Transportation and Gathering [Member]
Significant Purchase And Supply Commitments [Line Items]
2012	55
2013	49
2014	37
2015	29
2016	29
2017 and Thereafter	267
Total	466
Operating Lease Obligations [Member]
Significant Purchase And Supply Commitments [Line Items]
2012	45
2013	27
2014	28
2015	27
2016	26
2017 and Thereafter	32
Total	185
FPSO Lease Obligation [Member]
Significant Purchase And Supply Commitments [Line Items]
2012	72	[1]
2013	72	[1]
2014	72	[1]
2015	70	[1]
2016	45	[1]
2017 and Thereafter	155	[1]
Total	$ 486	[1]

[1] Annual lease payments, net to our interest, exclude regular maintenance and operational costs, and began during fourth quarter of 2011 once the Aseng FPSO initiated producing operations. See Note 12. Long-Term Debt.