INVESTMENTS AND RELATED-PARTY TRANSACTIONS (Details) (USD $)	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
RELATED-PARTY TRANSACTIONS
Purchases from EHP as percent of total related party purchase		90.00%	92.00%
Purchases from related parties	$ 10,000,000	$ 153,000,000	$ 138,000,000
Sales to related parties	392,000,000	440,000,000	291,000,000
Services to related parties	10,000,000	2,000,000	2,000,000
Advances and amounts due from related parties	32,000,000	135,000,000	123,000,000
Amounts due to related parties	21,000,000	383,000,000	112,000,000
Equity Method Investments
Equity method investment amounts	2,100,000,000	2,000,000,000
Equity investments dividends paid	349,000,000	217,000,000	139,000,000
Cumulative undistributed earnings of equity-method investees	400,000,000
Excess of investments in equity investees over the underlying equity in net assets	1,100,000,000
Excess of investments in equity investees over the underlying equity in net assets, which represents goodwill	1,000,000,000
Excess of investments in equity investees over the underlying equity in net assets, related to assets other than goodwill	134,000,000
Equity-method investments financial information summarized by Income Statement line item
Revenues	2,439,000,000	1,759,000,000	1,080,000,000
Costs and expenses	2,046,000,000	1,482,000,000	853,000,000
Net income	393,000,000	277,000,000	227,000,000
Equity-method investments financial information summarized by Balance Sheet line item
Current assets	2,230,000,000	2,041,000,000
Non-current assets	4,381,000,000	3,965,000,000
Current liabilities	1,532,000,000	1,323,000,000
Long-term debt	2,305,000,000	2,454,000,000
Other non-current liabilities	168,000,000	119,000,000
Stockholders' equity	$ 2,606,000,000	$ 2,110,000,000
EHP and Dolphin Energy
RELATED-PARTY TRANSACTIONS
Sales to related party (as a percent)		44.00%	63.00%
Dolphin Energy
EQUITY INVESTMENTS
Equity method investment ownership percentage	24.50%
Ownership interest in oil and gas properties (as a percent)	24.50%
Number of separate economic interests comprising investment in unconsolidated affiliate	2
RELATED-PARTY TRANSACTIONS
Sales to related party (as a percent)	16.00%
Elk Hills Power
EQUITY INVESTMENTS
Equity method investment ownership percentage		50.00%
Equity method investment additional ownership percentage		50.00%
Total ownership percentage		100.00%
General Partner of Plains All American Pipeline
EQUITY INVESTMENTS
Equity method investment ownership percentage	35.00%
RELATED-PARTY TRANSACTIONS
Sales to related party (as a percent)	76.00%	50.00%	26.00%
Oleoducto de Crudos Pesados Ltd. (OCP)
EQUITY INVESTMENTS
Equity method investment ownership percentage	14.00%