Equity - Non-controlling Interest (Details) - The Company	6 Months Ended	12 Months Ended
Jun. 30, 2018	Dec. 31, 2017
Class of Stock [Line Items]
Economic interests percentage	38.58%	38.12%
NuDevco Retail and Retailco
Class of Stock [Line Items]
Economic interests percentage	61.42%	61.88%

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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