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Business Segment Information (Details Textual)	9 Months Ended
	Sep. 30, 2018 Segment
Business Segment Information (Textual)
Number of reportable segments	3
GEIC [Member]
Business Segment Information (Textual)
Company's investment, ownership percentage in subsidiary	99.30%
GRE [Member]
Business Segment Information (Textual)
Company's investment, ownership percentage in subsidiary	100.00%
GOGAS [Member]
Business Segment Information (Textual)
Company's investment, ownership percentage in subsidiary	97.00%
Afek [Member]
Business Segment Information (Textual)
Company's investment, ownership percentage in subsidiary	86.10%

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- Definition

Number of segments reported by the entity. A reportable segment is a component of an entity for which there is an accounting requirement to report separate financial information on that component in the entity's financial statements.

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- Definition

Percentage of subsidiary's or equity method investee's stock owned by parent immediately after all stock transactions.

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