Derivatives (Details 3) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012 Occidental's production, Sales contracts Oil (in barrels) bbl	Dec. 31, 2011 Occidental's production, Sales contracts Oil (in barrels) bbl	Jun. 30, 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	Jun. 30, 2012 Third-party marketing and trading activities, Purchase contracts Natural Gas (in billion cubic feet) billioncubicfeet	Dec. 31, 2011 Third-party marketing and trading activities, Purchase contracts Natural Gas (in billion cubic feet) billioncubicfeet	Jun. 30, 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	Jun. 30, 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	Jun. 30, 2012 Third-party marketing and trading activities, Sales contracts Natural Gas (in billion cubic feet) billioncubicfeet	Dec. 31, 2011 Third-party marketing and trading activities, Sales contracts Natural Gas (in billion cubic feet) billioncubicfeet	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					14,000,000	9,000,000	158,000,000	109,000,000	342	481	1,000,000	4,000,000	152,000,000	109,000,000	451	723	1,000,000
Net Gains (Losses) from derivatives not designated as hedging instruments. (in dollars)	$ (86)	$ 77	$ (35)	$ 106