Basis Of Presentation (Stock-Based Awards, Lapses, Exercises And Forfeitures) (Details)	6 Months Ended
	Jun. 30, 2011
Restricted Stock Equity Awards [Member]
Outstanding at December 31, 2010	2,559,779
Awards granted	427,384
Awards vested	(1,015,713)
Awards forfeited	(37,914)
Outstanding at June 30, 2011	1,933,536
Restricted Stock Liability Awards [Member]
Outstanding at December 31, 2010	215,134
Awards granted	182,982
Awards vested	(63,556)
Awards forfeited	(11,931)
Outstanding at June 30, 2011	322,629
Performance Units [Member]
Outstanding at December 31, 2010	263,729
Awards granted	43,495
Awards vested	(14,807)
Outstanding at June 30, 2011	292,417
Stock Options [Member]
Outstanding at December 31, 2010	507,539
Awards granted	86,903
Options exercised	(15,290)
Outstanding at June 30, 2011	579,152
Pioneer Southwest LTIP Restricted Units [Member]
Outstanding at December 31, 2010	12,212
Awards granted	6,812
Awards vested	(11,532)
Outstanding at June 30, 2011	7,492
Pioneer Southwest LTIP Phantom Units [Member]
Outstanding at December 31, 2010	35,118
Awards granted	30,039
Outstanding at June 30, 2011	65,157