Acquistions (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended	9 Months Ended
Dec. 31, 2011 acres	Sep. 30, 2011 acres
Eagle Ford Hilcorp [Member]
Asset acquisition [Line Items]
Gas and oil acreages, net	141,000
Eagle Ford Additional [Member]
Asset acquisition [Line Items]
Gas and oil acreages, net	19,000
Eagle Ford Tag Along [Member]
Asset acquisition [Line Items]
Gas and oil acreages, net	6,800
Eagle Ford [Member]
Asset acquisition [Line Items]
Acquisition Costs	$ 4,500	$ 202
Gas and oil acreages, net	167,000	45,000

The capitalized costs incurred to purchase, lease or otherwise acquire a property, including costs of lease bonuses and options to purchase or lease properties, the portion of costs applicable to minerals when land including mineral rights is purchased in fee, brokers' fees, recording fees, legal costs, and other costs incurred in acquiring properties.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 10

-Paragraph c

-Subparagraph 3(ii)(A)

-Article 4

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Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration