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Description of Business and Summary of Significant Accounting Policies (Details Textual) $ in Thousands		3 Months Ended					12 Months Ended
	Nov. 30, 2019	Sep. 30, 2019	Mar. 31, 2019	Dec. 31, 2018 USD ($) Segment	Sep. 30, 2018	Mar. 31, 2018	Dec. 31, 2019 USD ($) Segment	Dec. 31, 2018 USD ($)	Apr. 12, 2019	Jan. 31, 2019 USD ($)	Oct. 25, 2018
Description of Business and Summary of Significant Accounting Policies (Textual)
Company's investment, ownership percentage in subsidiary							100.00%
Amount of advertising expense included in selling general and administrative expense							$ 4,100	$ 2,400
Description of percentage of consolidated revenue from utility companies							The percentage of consolidated revenues from customers by utility company that equal or exceed 10% of consolidated revenues in the period (no other single utility company accounted for more than 10% of consolidated revenues in these periods.
Description of percentage of consolidated gross trade accounts receivable by utility companies							The percentage of consolidated revenues from customers by utility company that equal or exceed 10% of consolidated revenues in the period (no other single utility company accounted for more than 10% of consolidated revenues in these periods.
Purchase method, description							The fair value of patents and trademarks, non-compete agreements and customer relationships acquired in a business combination accounted for under the purchase method are amortized over their estimated useful lives as follows: patents and trademarks are amortized on a straight-line basis over 5 to 20-year period; non-compete agreements are amortized on a straight-line basis over 2 to 3-year term; and customer relationships are amortized ratably over the 2 or 9 year period.
Percentage of electricity revenue generated in given period		31.80%			29.50%
Percentage of gas revenue generated in given period			46.90%			50.30%
Percentage of outstanding membership interests											60.00%
Number of reportable segments \| Segment							3
Distribution and handling costs							$ 300	100
Restricted cash, description							The Company adopted the amendments in this ASU on January 1, 2018. For the year ended December 31, 2017, $0.1 million and $10.0 million of changes in restricted cash balances that was previously presented within operating and financing activities, respectively, in the consolidated statement of cash flows has been excluded from the cash flows used in operating and financing activities and the effect of exchange rate changes increased by $0.6 million due to the retrospective adoption of ASU 2016-18. Restricted cash of $2.0 million and $11.9 million at December 31, 2017 and 2016, respectively, have been included with the cash and cash equivalents when reconciling the beginning of year and end of year total amounts on the consolidated statement of cash flows for the year ended December 31, 2017.
Percentage of divestiture interest					37.50%				60.00%
Impairment of goodwill							$ 400
Current lease liabilities										$ 400
Non current lease liabilities										2,000
Operating lease right of use Asset										2,400
Accumulated deficit				$ (53,939)			$ (59,671)	(53,939)		$ 300
Atid Drilling Ltd. [Member]
Description of Business and Summary of Significant Accounting Policies (Textual)
Percentage of divestiture interest							37.50%
Customer Relationships [Member] \| Maximum [Member]
Description of Business and Summary of Significant Accounting Policies (Textual)
Amortization period							9 years
Customer Relationships [Member] \| Minimum [Member]
Description of Business and Summary of Significant Accounting Policies (Textual)
Amortization period							2 years
Patents and trademarks [Member]
Description of Business and Summary of Significant Accounting Policies (Textual)
Amortization period							20 years
Non-compete agreement [Member] \| Maximum [Member]
Description of Business and Summary of Significant Accounting Policies (Textual)
Amortization period							3 years
Non-compete agreement [Member] \| Minimum [Member]
Description of Business and Summary of Significant Accounting Policies (Textual)
Amortization period							2 years
Genie Retail Energy [Member]
Description of Business and Summary of Significant Accounting Policies (Textual)
Company's investment, ownership percentage in subsidiary							100.00%
Genie Retail Energy One [Member]
Description of Business and Summary of Significant Accounting Policies (Textual)
Company's investment, ownership percentage in subsidiary							100.00%
GRE International [Member]
Description of Business and Summary of Significant Accounting Policies (Textual)
Company's investment, ownership percentage in subsidiary							73.00%
Lumo [Member]
Description of Business and Summary of Significant Accounting Policies (Textual)
Company's investment, ownership percentage in subsidiary	89.00%						80.00%
Total capitalized customer acquisition costs							$ 800
Capitalized and amortized Period							eighteen months
Customer acquisition costs				$ 100			$ 600	$ 100
Afek Oil and Gas, Ltd. [Member]
Description of Business and Summary of Significant Accounting Policies (Textual)
Company's investment, ownership percentage in subsidiary							86.10%
Number of reportable segments \| Segment				1
Genie Energy International Corporation [Member]
Description of Business and Summary of Significant Accounting Policies (Textual)
Company's investment, ownership percentage in subsidiary							99.30%
GOGAS [Member]
Description of Business and Summary of Significant Accounting Policies (Textual)
Number of reportable segments \| Segment				1
GES [Member]
Description of Business and Summary of Significant Accounting Policies (Textual)
Company's investment, ownership percentage in subsidiary							97.00%