Derivatives (Details 3) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011 Occidental's production, Sales contracts Crude Oil barrel	Dec. 31, 2010 Occidental's production, Sales contracts Crude Oil barrel	Sep. 30, 2011 Third-party marketing and trading activities, Purchase contracts Crude Oil barrel	Dec. 31, 2010 Third-party marketing and trading activities, Purchase contracts Crude Oil barrel	Sep. 30, 2011 Third-party marketing and trading activities, Purchase contracts Natural Gas Cubicfeet	Dec. 31, 2010 Third-party marketing and trading activities, Purchase contracts Natural Gas Cubicfeet	Sep. 30, 2011 Third-party marketing and trading activities, Purchase contracts Precious metals troyounce	Dec. 31, 2010 Third-party marketing and trading activities, Purchase contracts Precious metals troyounce	Sep. 30, 2011 Third-party marketing and trading activities, Sales contracts Crude Oil barrel	Dec. 31, 2010 Third-party marketing and trading activities, Sales contracts Crude Oil barrel	Sep. 30, 2011 Third-party marketing and trading activities, Sales contracts Natural Gas Cubicfeet	Dec. 31, 2010 Third-party marketing and trading activities, Sales contracts Natural Gas Cubicfeet	Sep. 30, 2011 Third-party marketing and trading activities, Sales contracts Precious metals troyounce	Dec. 31, 2010 Third-party marketing and trading activities, Sales contracts Precious metals troyounce
Gross volumes of commodity derivatives not designated as hedging instruments
Gross volumes of commodity derivative					9,000,000	8,000,000	173,000,000	136,000,000	682,000,000,000	833,000,000,000	3,000,000	13,000,000	170,000,000	144,000,000	801,000,000,000	1,156,000,000,000	1,000,000	1,000,000
Net Gains (Losses) from derivatives not designated as hedging instruments. (in dollars)	$ (237)	$ 15	$ (47)	$ 59