Derivatives (Details 3) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011	Mar. 31, 2012 Occidental's production, Sales contracts Oil (in barrels) bbl	Dec. 31, 2011 Occidental's production, Sales contracts Oil (in barrels) bbl	Mar. 31, 2012 Third-party marketing and trading activities, Purchase contracts Oil (in barrels) bbl	Dec. 31, 2011 Third-party marketing and trading activities, Purchase contracts Oil (in barrels) bbl	Mar. 31, 2012 Third-party marketing and trading activities, Purchase contracts Natural Gas (in cubic feet) ft3	Dec. 31, 2011 Third-party marketing and trading activities, Purchase contracts Natural Gas (in cubic feet) ft3	Mar. 31, 2012 Third-party marketing and trading activities, Purchase contracts Precious metals (in troy ounces) ozt	Dec. 31, 2011 Third-party marketing and trading activities, Purchase contracts Precious metals (in troy ounces) ozt	Mar. 31, 2012 Third-party marketing and trading activities, Sales contracts Oil (in barrels) bbl	Dec. 31, 2011 Third-party marketing and trading activities, Sales contracts Oil (in barrels) bbl	Mar. 31, 2012 Third-party marketing and trading activities, Sales contracts Natural Gas (in cubic feet) ft3	Dec. 31, 2011 Third-party marketing and trading activities, Sales contracts Natural Gas (in cubic feet) ft3	Dec. 31, 2011 Third-party marketing and trading activities, Sales contracts Precious metals (in troy ounces) ozt
Outstanding commodity derivatives contracts not designated as hedging instruments
Gross volumes			12,000,000	9,000,000	252,000,000	109,000,000	444,000,000,000	481,000,000,000	1,000,000	4,000,000	251,000,000	109,000,000	632,000,000,000	723,000,000,000	1,000,000
Net Gains from derivatives not designated as hedging instruments. (in dollars)	$ 51	$ 29