Incentive Plans (Schedule Of Integral Part Of Consolidated Financial Statements) (Details) (USD $)	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010
Phantom Unit Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted Average Grant-Date Fair Value, Shares granted	$ 32.16	$ 22.74
Pioneer Southwest LTIP [Member] | Restricted Unit Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Shares/Units, Outstanding at beginning of year	12,212
Number of Units granted	6,812
Number of Units Lapse of restrictions	(11,532)
Number of Shares/Units, Outstanding at end of year	7,492
Weighted Average Grant-Date Fair Value, Outstanding at beginning of year	$ 21.84
Weighted Average Grant-Date Fair Value, Shares granted	$ 29.35
Weighted Average Grant Date Fair Value Lapse of restrictions	$ 21.97
Weighted Average Grant-Date Fair Value, Outstanding at end of year	$ 28.47
Pioneer Southwest LTIP [Member] | Phantom Unit Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Shares/Units, Outstanding at beginning of year	35,118
Number of Units granted	30,039
Number of Units Lapse of restrictions
Number of Shares/Units, Outstanding at end of year	65,157
Weighted Average Grant-Date Fair Value, Outstanding at beginning of year	$ 22.74
Weighted Average Grant-Date Fair Value, Shares granted	$ 32.16
Weighted Average Grant Date Fair Value Lapse of restrictions
Weighted Average Grant-Date Fair Value, Outstanding at end of year	$ 27.08