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Property And Equipment (Narrative) (Details) (USD $) | 3 Months Ended | 9 Months Ended |  |  |  |  |  |  |  | 1 Months Ended | 9 Months Ended
--- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | ---
Sep. 30, 2014 | Sep. 30, 2013 | Sep. 30, 2014 | Sep. 30, 2013 | Dec. 31, 2013 | Sep. 30, 2014 Diamondback Energy, Inc [Member] | Oct. 11, 2012 Diamondback Energy, Inc [Member] | Sep. 30, 2014 Diamondback [Member] | Oct. 31, 2012 Diamondback [Member] | Oct. 11, 2012 Diamondback [Member] | May 07, 2012 Diamondback [Member] | Jan. 31, 2013 Diamondback [Member] Accounts Receivable - Related Party [Member] | Sep. 30, 2014 Minimum [Member] | Sep. 30, 2014 Maximum [Member]
Property, Plant and Equipment [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Cumulative capitalization of general and administrative costs incurred and capitalized to the full cost pool | $ 66,600,000 |  | $ 66,600,000 |  |  |  |  |  |  |  |  |  |  |
Capitalized general and administrative costs | 5,900,000 | 3,500,000 | 19,100,000 | 9,600,000 |  |  |  |  |  |  |  |  |  |
Capitalized costs of oil and natural gas properties excluded from amortization | 1,452,730,000 |  | 1,452,730,000 |  | 950,590,000 |  |  |  |  |  |  |  |  |
Expected number of years amortization will commence |  |  |  |  |  |  |  |  |  |  |  |  | 3 years | 5 years
Investment (shares) |  |  |  |  |  | 942,000 | 7,914,036 | 942,000 |  | 7,914,036 |  |  |  |
Promissory note receivable |  |  |  |  |  |  |  |  |  | 63,600,000 |  |  |  |
Payment received from Diamondback |  |  | $ 80,767,000 | $ 22,058,000 |  |  |  |  |  |  |  | $ 18,600,000 |  |
Ownership interest |  |  |  |  |  | 1.70% |  |  | 21.40% |  | 35.00% |  |  |

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