Acquisitions and Divestitures (Discontinued Operations Narrative) (Details) (USD $)	3 Months Ended		6 Months Ended			12 Months Ended	6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012 Pioneer South Africa [Member]	Dec. 31, 2011 Pioneer Tunisia [Member]	Jun. 30, 2011 BOEMRE [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Proceeds from divestiture of interest in consolidated subsidiaries					$ 52,000,000	$ 802,500,000
Disposal group, including discontinued operation, gross profit (loss)						645,200,000
Interest and other	$ 0	$ 35,000	$ 20,000	$ 4,971,000			$ 2,000,000