Incentive Plans (Tables)

6 Months Ended

Jun. 30, 2012

Defined Benefit Pension Plans and Defined Benefit Postretirement Plans Disclosure [Abstract]

Schedule of accumulated postretirement benefit obligations

The following table summarizes the activity that occurred during the six months ended June 30, 2012, for each type of share-based incentive award issued by Pioneer:

	Restricted Stock Equity Awards		Restricted Stock Liability Awards		Performance Units	Stock Options		Pioneer Southwest LTIP Restricted Units		Pioneer Southwest LTIP Phantom Units
Outstanding at December 31, 2011	1,857,612		322,925		114,128	564,044		7,492		65,157
Awards granted	897,591		223,375		47,875	98,819		7,496		37,487
Awards vested	(1,199,536	)	(115,700	)	—	—		(7,492	)	—
Options exercised	—		—		—	(64,509	)	—		—
Awards forfeited	(15,145	)	(10,342	)	—	—		—		—
Outstanding as of June 30, 2012	1,540,522		420,258		162,003	598,354		7,496		102,644