Acquisitions and Divestitures (Discontinued Operations Narrative) (Details) (USD $)	12 Months Ended						3 Months Ended
	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012		Mar. 31, 2012	Dec. 17, 2013
Discontinued Operations Assets and Liabilities Included in Assets and Liabilities Held for Sale [Line Items]
Gain on disposition of assets, net	$ 9,000,000		$ 209,000,000		$ 46,000,000
Proceeds from disposition of assets, net of cash sold	877,000,000		711,000,000		96,000,000
Issuance of treasury stock to acquire outstanding PSE units, shares			3,960,000
Tangible Asset Impairment Charges	8,000,000	[1]	62,000,000	[1]	6,000,000	[1]
Impairment of oil and gas properties	0		1,495,000,000		0
Gaines Dawson [Member]
Discontinued Operations Assets and Liabilities Included in Assets and Liabilities Held for Sale [Line Items]
Gain on disposition of assets, net	2,000,000
Proceeds from disposition of assets, net of cash sold	72,000,000
Wolfcamp [Member]
Discontinued Operations Assets and Liabilities Included in Assets and Liabilities Held for Sale [Line Items]
Gain on disposition of assets, net			181,000,000
Proceeds from disposition of assets, net of cash sold			624,000,000
Joint Venture Investment Ownership Percentage			40.00%
Significant Acquisitions and Disposals, Acquisition Costs or Sale Proceeds			1,800,000,000
Maximum Payments From Related Party For Exploration Drilling And Completion Costs	575,000,000		1,200,000,000
Payments From Related Party For Exploration Drilling And Completion Costs Percent			75.00%
West Panhandle [Member]
Discontinued Operations Assets and Liabilities Included in Assets and Liabilities Held for Sale [Line Items]
Gain on disposition of assets, net			22,000,000
Proceeds from disposition of assets, net of cash sold			38,000,000
Eagle Ford Shale [Member]
Discontinued Operations Assets and Liabilities Included in Assets and Liabilities Held for Sale [Line Items]
Gain on disposition of assets, net					43,000,000
Proceeds from disposition of assets, net of cash sold					55,000,000
Other Assets [Member]
Discontinued Operations Assets and Liabilities Included in Assets and Liabilities Held for Sale [Line Items]
Gain on disposition of assets, net	4,000,000		5,000,000		3,000,000
Lease Contract for Next 12 Months [Member]
Discontinued Operations Assets and Liabilities Included in Assets and Liabilities Held for Sale [Line Items]
Drilling rigs leased	12
Lease Contract for Year 2 [Member]
Discontinued Operations Assets and Liabilities Included in Assets and Liabilities Held for Sale [Line Items]
Drilling rigs leased	8
Discontinued Operations [Member]
Discontinued Operations Assets and Liabilities Included in Assets and Liabilities Held for Sale [Line Items]
Gain on disposition of assets, net	9,000,000		9,000,000		41,000,000
Impairment of oil and gas properties	305,000,000	[2]	729,000,000	[2]	533,000,000	[2]
Discontinued Operations [Member] | Hugoton field [Member]
Discontinued Operations Assets and Liabilities Included in Assets and Liabilities Held for Sale [Line Items]
Proceeds from disposition of assets, net of cash sold	328,000,000
Impairment of oil and gas properties	34,000,000
Discontinued Operations [Member] | Pioneer Alaska [Member]
Discontinued Operations Assets and Liabilities Included in Assets and Liabilities Held for Sale [Line Items]
Gain on disposition of assets, net					13,000,000
Proceeds from disposition of assets, net of cash sold	267,000,000				10,000,000
Impairment of oil and gas properties	97,000,000		539,000,000
Discontinued Operations [Member] | Barnett Shale Field [Member]
Discontinued Operations Assets and Liabilities Included in Assets and Liabilities Held for Sale [Line Items]
Gain on disposition of assets, net			9,000,000
Proceeds from disposition of assets, net of cash sold	150,000,000		34,000,000
Impairment of oil and gas properties	174,000,000		190,000,000		533,000,000
Discontinued Operations [Member] | Pioneer South Africa [Member]
Discontinued Operations Assets and Liabilities Included in Assets and Liabilities Held for Sale [Line Items]
Gain on disposition of assets, net					29,000,000
Proceeds from disposition of assets, net of cash sold					16,000,000		60,000,000
Sendero [Member]
Discontinued Operations Assets and Liabilities Included in Assets and Liabilities Held for Sale [Line Items]
Proceeds from Divestiture of Interest in Consolidated Subsidiaries	31,000,000
Tangible Asset Impairment Charges			25,000,000
Limited Partner Interest [Member]
Discontinued Operations Assets and Liabilities Included in Assets and Liabilities Held for Sale [Line Items]
Partners' Capital Account, Acquisitions	5
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net	54,000,000
Pioneer Southwest [Member]
Discontinued Operations Assets and Liabilities Included in Assets and Liabilities Held for Sale [Line Items]
Share Per Unit Exchange Ratio								0.2325
Premier Silica [Member]
Discontinued Operations Assets and Liabilities Included in Assets and Liabilities Held for Sale [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net					$ 297,000,000

[1] Primarily represents charges of $8 million and $36 million to reduce excess materials and supplies inventories to their market values for the years ended December 31, 2014 and 2013, respectively, and a charge of $25 million for the year ended December 31, 2013 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] (b)Represents noncash impairment charges of $97 million and $539 million on Pioneer Alaska net assets during the years ended December 31, 2014 and 2013, respectively, noncash impairment charges of $174 million, $190 million and $533 million on the Company's net assets in the Barnett Shale field during the years ended December 31, 2014, 2013 and 2012, respectively, and a noncash impairment charge of $34 million on the Company's net assets in the Hugoton field during the year ended December 31, 2014. See Note D for additional information regarding the noncash impairment charges.