Business Segment Information (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2017	Mar. 31, 2016
Operating results for the business segments
Revenues (restated see Note 2)	$ 71,405	$ 58,879
Income (loss) from operations (restated see Note 2)	5,196	5,999
Exploration	851	1,691
Equity in the net loss of AMSO, LLC		222
GRE [Member]
Operating results for the business segments
Income (loss) from operations (restated see Note 2)	8,974	10,698
Exploration
Equity in the net loss of AMSO, LLC
Afek [Member]
Operating results for the business segments
Income (loss) from operations (restated see Note 2)	(1,286)	(1,827)
Exploration	851	1,691
Equity in the net loss of AMSO, LLC
GOGAS [Member]
Operating results for the business segments
Income (loss) from operations (restated see Note 2)	(97)	(469)
Exploration
Equity in the net loss of AMSO, LLC		222
Corporate [Member]
Operating results for the business segments
Income (loss) from operations (restated see Note 2)	(2,395)	(2,403)
Exploration
Equity in the net loss of AMSO, LLC

- Definition

Exploration expenses (including prospecting) related to oil and gas producing entities and would be included in operating expenses of that entity. Costs incurred in identifying areas that may warrant examination and in examining specific areas that are considered to have prospects of containing oil and gas reserves, including costs of drilling exploratory wells and exploratory-type stratigraphic test wells. Exploration costs may be incurred both before acquiring the related property (sometimes referred to in part as prospecting costs) and after acquiring the property. Principal types of exploration costs, which include depreciation and applicable operating costs of support equipment and facilities and other costs of exploration activities, are: (i) Costs of topographical, geographical and geophysical studies, rights of access to properties to conduct those studies, and salaries and other expenses of geologists, geophysical crews, and others conducting those studies. Collectively, these are sometimes referred to as geological and geophysical or "G&G" costs. (ii) Costs of carrying and retaining undeveloped properties, such as delay rentals, ad valorem taxes on properties, legal costs for title defense, and the maintenance of land and lease records. (iii) Dry hole contributions and bottom hole contributions. (iv) Costs of drilling and equipping exploratory wells. (v) Costs of drilling exploratory-type stratigraphic test wells.

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