Derivatives (Details 3) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011 Occidental's production, Sales contracts Crude Oil (in barrels)	Dec. 31, 2010 Occidental's production, Sales contracts Crude Oil (in barrels)	Jun. 30, 2011 Third-party marketing and trading activities, Purchase contracts Crude Oil (in barrels)	Dec. 31, 2010 Third-party marketing and trading activities, Purchase contracts Crude Oil (in barrels)	Jun. 30, 2011 Third-party marketing and trading activities, Purchase contracts Natural Gas (in cubic feet)	Dec. 31, 2010 Third-party marketing and trading activities, Purchase contracts Natural Gas (in cubic feet)	Jun. 30, 2011 Third-party marketing and trading activities, Purchase contracts Precious metals (million troy ounces)	Dec. 31, 2010 Third-party marketing and trading activities, Purchase contracts Precious metals (million troy ounces)	Jun. 30, 2011 Third-party marketing and trading activities, Sales contracts Crude Oil (in barrels)	Dec. 31, 2010 Third-party marketing and trading activities, Sales contracts Crude Oil (in barrels)	Jun. 30, 2011 Third-party marketing and trading activities, Sales contracts Natural Gas (in cubic feet)	Dec. 31, 2010 Third-party marketing and trading activities, Sales contracts Natural Gas (in cubic feet)	Jun. 30, 2011 Third-party marketing and trading activities, Sales contracts Precious metals (million troy ounces)	Dec. 31, 2010 Third-party marketing and trading activities, Sales contracts Precious metals (million troy ounces)
Gross volumes of commodity derivatives not designated as hedging instruments
Gross volumes of commodity derivative					9,000,000	8,000,000	205,000,000	136,000,000	888,000,000,000	833,000,000,000	1,000,000	13,000,000	191,000,000	144,000,000	998,000,000,000	1,156,000,000,000	1,000,000	1,000,000
Net Gains (Losses) from derivatives not designated as hedging instruments. (in dollars)	$ 200	$ 67	$ 189	$ 44