Equity Investment in Savoy (Condensed Balance Sheet - Savoy) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Current assets	$ 84,409us-gaap_AssetsCurrent	$ 40,170us-gaap_AssetsCurrent
Other	18,849us-gaap_OtherAssetsNoncurrent	15,382us-gaap_OtherAssetsNoncurrent
Total assets	579,585us-gaap_Assets	259,199us-gaap_Assets
Total liabilities	389,710us-gaap_Liabilities	77,079us-gaap_Liabilities
Total liabilities and stockholders' equity	579,585	259,199
Savoy [Member]
Current assets	14,863	29,182
Oil and gas properties, net	27,549	25,408
Other	852	260
Total assets	43,264	54,850
Total liabilities	10,079	16,447
Partners' capital	33,185	38,403
Total liabilities and stockholders' equity	$ 43,264	$ 54,850

Sum of the carrying amounts as of the balance sheet date of all assets that are recognized. Assets are probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

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Sum of the carrying amounts as of the balance sheet date of all assets that are expected to be realized in cash, sold, or consumed within one year (or the normal operating cycle, if longer). Assets are probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

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Sum of the carrying amounts as of the balance sheet date of all liabilities that are recognized. Liabilities are probable future sacrifices of economic benefits arising from present obligations of an entity to transfer assets or provide services to other entities in the future.

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Oil and gas properties net of accumulated depreciation, depletion, amortization, impairment, and abandonment, carried under the successful effort method.

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Aggregate carrying amount, as of the balance sheet date, of noncurrent assets not separately disclosed in the balance sheet. Noncurrent assets are expected to be realized or consumed after one year (or the normal operating cycle, if longer).

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