Property, Plant and Equipment - Summary of Impairment Expense by Project (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016
Total Impairment	$ 11,436	$ 1,673
Kingsville Dome Project [Member]
Total Impairment	140	160
Butler Ranch Project [Member]
Total Impairment		579
Sejita Dome Project [Member]
Total Impairment		534
Nell Project [Member]
Total Impairment		209
Jack Pump Project [Member]
Total Impairment		191
Cebolleta/Juan Tafoya Property [Member]
Total Impairment	$ 11,296

Amount of write-down of assets recognized in the income statement. Includes, but is not limited to, losses from tangible assets, intangible assets and goodwill.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 360
-SubTopic 10
-Section 45
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=68055307&loc=d3e2420-110228

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3602-108585

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