Disclosures About Fair Value Measurements Disclosures About Fair Value Measurements (Fair Value of Assets Classified as Held For Sale) (Details) (USD $)	12 Months Ended
	Dec. 31, 2013		Dec. 31, 2012		Dec. 31, 2011
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impairment of oil and gas properties	$ 1,495,242,000		$ 0		$ 354,408,000
Tangible Asset Impairment Charges	61,812,000	[1]	5,719,000	[1]	3,126,000	[1]
Pioneer Alaska [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value of Asset Group	350,600,000
Barnett Shale Field [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value of Asset Group	180,400,000
Sendero [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value of Asset Group	31,400,000
Tangible Asset Impairment Charges	25,500,000
Discontinued Operations [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impairment of oil and gas properties	729,305,000	[2]	532,589,000	[2]	0	[2]
Discontinued Operations [Member] | Pioneer Alaska [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impairment of oil and gas properties	539,800,000
Discontinued Operations [Member] | Barnett Shale Field [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impairment of oil and gas properties	$ 189,500,000

[1] Represents charges of $36.3 million to reduce excess materials and supplies inventories to their market value and a charge of $25.5 million to reduce the carrying value of Sendero to its estimated fair value. See Notes C and D for additional information on the fair value of Sendero and material and supplies inventory, respectively.

[2] (c)Represents a noncash impairment charge of $539.8 million on Pioneer Alaska net assets during the year ended December 31, 2013 and noncash impairment charges of $189.5 million and $532.6 million during the years ended December 31, 2013 and 2012, respectively, on the Company's net assets in the Barnett Shale field. See Note D for additional information regarding the noncash impairment charges.