Note 12 - Long-term Debt and Credit Agreements - Long-term Debt (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
	$ 681,548	$ 640,133
Less current portion	(53,729)	(51,425)
Non current portion	627,819	588,708
Recourse Debt	274,983	280,332
Less current portion	(12,242)	(11,229)
Non current portion	262,741	269,103
Other Loans, Limited and Non-recourse [Member]
Non-Recourse Debt	6,368
Loan Agreement With OPIC The Olkaria III Power Plant [Member]
Non-Recourse Debt	246,630	264,624
Loan Agreement with Banco Industrial S.A. and Westrust Bank (International) Limited [Member]
Non-Recourse Debt	36,750	40,250
Ormat Funding Corp [Member]
Non-Recourse Debt	17,026	29,968
Orcal Geothermal Inc [Member]
Non-Recourse Debt	35,181	43,332
Don A. Campbell 1 ("DAC1") [Member]
Non-Recourse Debt	92,361
OFC Two Senior Secured Notes [Member]
Non-Recourse Debt	247,232	261,959
Senior Unsecured Bonds [Member]
Recourse Debt	204,332	249,981
Institutional Investors [Member]
Recourse Debt	3,333	6,667
Olkaria III DEG [Member]
Recourse Debt	65,789	23,684
Loan From Commercial Bank [Member]
Recourse Debt	1,529
Revolving Credit Lines With Banks [Member]
Recourse Debt