Acquisitions and Divestitures (Narrative) (Details) (USD $)	3 Months Ended			12 Months Ended		3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Dec. 31, 2012	Dec. 31, 2012 Pioneer South Africa [Member]	Mar. 31, 2012 Pioneer South Africa [Member]	Mar. 31, 2013 Wolfcamp [Member] Rate	Mar. 31, 2013 West Panhandle [Member]	Mar. 31, 2012 Eagle Ford Shale [Member]
Acquisitions and Divestitures [Line Items]
Business acquisition, cost of acquired entity, purchase price			$ 297,100,000
Gains (Losses) on Sales of Assets	24,417,000	43,596,000					21,700,000	42,600,000
Proceeds from Sale of Productive Assets	46,184,000	58,514,000					37,400,000	54,700,000
Business Combination, Consideration Transferred					60,000,000	1,700,000,000
Proceeds from Divestiture of Interest in Consolidated Subsidiaries				15,900,000		522,000,000
Gains Losses On Sales Of Assets Discontinued Operations				28,600,000
Oil And Gas Revenue From Discontinued Operations		19,600,000
Discontinued Operation, Income (Loss) from Discontinued Operation, before Income Tax		17,400,000
Joint Venture Investment Ownership Percentage						40.00%
Maximum Payments From Related Party For Exploration Drilling And Completion Costs						$ 1,200,000,000
Payments From Related Party For Exploration Drilling And Completion Costs Percent						75.00%