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Property And Equipment (Narrative) (Details) (USD $) | 3 Months Ended |  |  |  |  |  | 1 Months Ended | 3 Months Ended |  |
--- | --- | --- | --- | --- | --- | --- | --- | --- | --- | ---
Mar. 31, 2014 | Mar. 31, 2013 | Dec. 31, 2013 | Mar. 31, 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] | Mar. 31, 2014 Minimum [Member] | Mar. 31, 2014 Maximum [Member] | Mar. 31, 2014 Diamondback Energy, Inc [Member] | May 07, 2012 Diamondback Energy, Inc [Member]
Property, Plant and Equipment [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Cumulative capitalization of general and administrative costs incurred and capitalized to the full cost pool | $ 53,800,000 |  |  |  |  |  |  |  |  |  |  |
Capitalized general and administrative costs | 6,300,000 | 2,900,000 |  |  |  |  |  |  |  |  |  |
Capitalized costs of oil and natural gas properties excluded from amortization | 1,138,085,000 |  | 950,590,000 |  |  |  |  |  |  |  |  |
Expected number of years amortization will commence |  |  |  |  |  |  |  |  | 3 years | 5 years |  |
Investment (shares) |  |  |  | 3,379,500 |  | 7,914,036 |  |  |  |  | 3,379,500 | 7,914,036
Promissory note receivable |  |  |  |  |  | 63,600,000 |  |  |  |  |  |
Payment received from Diamondback | $ 27,944,000 | $ (3,592,000) |  |  |  |  |  | $ 18,600,000 |  |  |  |
Ownership interest |  |  |  |  | 21.40% |  | 35.00% |  |  |  | 6.70% |

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