Incentive Plans (Tables)

12 Months Ended

Dec. 31, 2011

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Schedule Of Compensation Expense For Each Type Of Incentive Award

	Year Ended December 31,
	2011		2010		2009
	(in thousands)
Restricted stock-equity awards (a)	$	32,861	$	31,712	$	31,929
Restricted stock-liability awards		10,882		4,900		—
Stock options (b)		2,936		1,522		629
Performance unit awards		4,500		4,635		4,868
Pioneer Southwest LTIP		761		475		217
Sendero Series B units		1,020		1,020		—
ESPP		125		1,034		907
Total	$	53,085	$	45,298	$	38,550
Income tax benefit	$	22,084	$	14,019	$	11,675

(a) For the year ended December 31, 2010, compensation expense included a charge of $1.3 million for the modification of equity awards associated with termination agreements made with 12 employees affected by the divestiture of the Company's Tunisian subsidiaries. The modification accelerated vesting of all unvested equity awards for the 12 participants to the closing date of the transaction. The $1.3 million charge, net of the associated tax benefit, is included in income from discontinued operations, net of tax, in the accompanying consolidated statement of operations for the year ended December 31, 2010.

(b) Cash proceeds received from stock option exercises during 2011, 2010 and 2009 amounted to $619 thousand, $4.8 million and $6.6 million, respectively.

Number Of Shares Available Under The Company's Long Term Incentive Plan

Approved and authorized awards	9,100,000
Awards issued after May 3, 2006	(5,705,600	)
Awards available for future grant	3,394,400

Schedule Of Restricted Stock Award Activity

	Equity Awards					Liability Awards
	Number of Shares			Weighted Average  Grant- Date Fair Value		Number of Shares
Outstanding at beginning of year		2,559,779		$	28.85		215,134
Shares granted		443,060		$	97.52		202,411
Shares forfeited		(63,105	)	$	54.51		(23,953	)
Shares vested		(1,082,122	)	$	36.41		(70,667	)
Outstanding at end of year		1,857,612		$	39.95		322,925

Schedule Of Stock Options Awards Activity

	Number of Shares			Weighted Average Exercise Price		Weighted Average Remaining Contractual Life		Aggregate Intrinsic  Value
						(in years)		(in thousands)
Nonstatutory stock options:
Outstanding at beginning of year		507,539		$	23.11
Options awarded		86,903		$	98.69
Options expired and forfeited		—		$	—
Options exercised		(30,398	)	$	20.36
Outstanding and expected to vest at end of year		564,044		$	34.90		8.10	$	30,786
Exercisable at end of year		26,905		$	22.64		7.63	$	1,798

Schedule Of Performance Unit Activity

	Number of Units (a)			Weighted  Average Grant-Date Fair Value
Beginning performance unit awards		263,729		$	28.91
Units granted		43,495		$	134.68
Units vested (b)		(193,096	)	$	16.25
Ending performance unit awards		114,128		$	90.64

(a) These amounts reflect the number of performance units granted. The actual payout of shares may be between zero percent and 250 percent of the performance units granted depending upon the total shareholder return ranking of the Company compared to peer companies at the vesting date.

(b) On December 31, 2011, the service period lapsed on 178,289 of these performance unit awards. The lapsed units earned 2.5 shares for each vested award representing 445,724 aggregate shares of common stock issued in 2012. On May 31, 2011, 14,807 units lapsed as part of the Tunisian divesture and earned 2.5 shares for each vested award, representing 37,018 of aggregate shares of common stock.

Schedule Of Employee Stock Purchase Plan

Approved and authorized shares	750,000
Shares issued	(625,003	)
Shares available for future issuance	124,997

Schedule Of Accumulated Postretirement Benefit Obligations

	Year Ended December 31,
	2011			2010			2009
	(in thousands)
Beginning accumulated postretirement benefit obligations	$	7,408		$	9,075		$	9,612
Net benefit payments		(1,323	)		(1,491	)		(1,430	)
Service costs		243			321			228
Net actuarial losses (gains)		813			(930	)		8
Accretion of interest		315			433			657
Ending accumulated postretirement benefit obligations	$	7,456		$	7,408		$	9,075

Schedule Of Future Postretirement Benefits

2012	$	854
2013	$	902
2014	$	953
2015	$	1,006
2016	$	995
Thereafter	$	2,746

Stock Options [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Schedule Of Weighted-Average Assumptions To Estimate The Fair Value

	2011			2010			2009
Expected option life - years		7			7			7
Volatility		47.6	%		46.8	%		43.0	%
Risk-free interest rate		2.9	%		3.4	%		3.3	%
Dividend yield		0.4	%		0.4	%		1.9	%

Performance Unit Awards [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Schedule Of Weighted-Average Assumptions To Estimate The Fair Value

	2011	2010	2009
Risk-free interest rate	1.32%	1.36%	1.33%
Range of volatilities	50.2% - 84.1%	50.4% - 83.0%	47.1% - 73.0%

Pioneer Southwest [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Number Of Awards Available Under Company's Long Term Incentive Plan

Approved and authorized awards	3,000,000
Awards issued after May 6, 2008	(106,252	)
Awards available for future grant	2,893,748

Schedule Of Integral Part Of Consolidated Financial Statements

	Restricted Unit Awards					Phantom Unit Awards
	Number of Units			Weighted Average Grant-Date Fair Value		Number of Units		Weighted Average Grant-Date Fair Value
Outstanding at beginning of year		12,212		$	21.84		35,118	$	22.74
Units granted		6,812		$	29.35		30,039	$	32.16
Lapse of restrictions		(11,532	)	$	21.97		—	$	—
Outstanding at end of year		7,492		$	28.47		65,157	$	27.08