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Note 20 - Transactions With Related Entities (Details Textual) - USD ($)			1 Months Ended	12 Months Ended
	Feb. 12, 2015	Apr. 01, 2009	Jul. 31, 2004	Dec. 31, 2017	Dec. 31, 2016	Feb. 11, 2015
Common Stock, Shares, Outstanding, Ending Balance				50,609,051	49,667,340
Corporate Costs And Other				$ 10,000
Other Research and Development Expense, Percentage				10.00%
Ormat Systems Ltd [Member]
Operating Lease, Monthly Rent		$ 77,000	$ 52,000
Ormat Industries Ltd. [Member]
Percentage of Public Float Before Transition to Noncontrolled Public Company						40.00%
Percentage of Public Float After Transition to Noncontrolled Public Company	76.00%
Share Exchange Shares Granted Per Share	0.2592
Conversion of Stock, Shares Issued	30,200,000
Stock Issued During Period, Shares, New Issues	3,000,000
Common Stock, Shares, Outstanding, Ending Balance	48,500,000					45,500,000
Sale of Stock, Consideration Received on Transaction	$ 15,400,000
Ormat Industries Ltd. [Member] \| Shares Issued to Self, Deducted [Member]
Conversion of Stock, Shares Issued	27,200,000
Ormat Industries Ltd. [Member] \| Sale of Stock, Other Assets Received [Member]
Sale of Stock, Consideration Received Per Transaction	$ 600,000
Ormat Industries Ltd. [Member] \| Sale of Stock, Land and Buildings Received [Member]
Sale of Stock, Consideration Received Per Transaction	12,100,000
Ormat Industries Ltd. [Member] \| Sale of Stock, Liabilities Assumed [Member]
Sale of Stock, Consideration Received Per Transaction	$ 500,000