Note 11 - Long-term Debt, Credit Agreements and Commercial Paper - Long-term Debt (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Limited Resource	$ 732,461	$ 775,547
Less current portion	(58,932)	(63,180)
Non current portion	673,529	712,367
Recourse Debt	474,514	510,832
Less current portion	(117,122)	(164,000)
Non current portion	357,392	346,832
Other Loans, Limited and Non-recourse [Member]
Non-Recourse Debt	8,997	6,241
Loan Agreement With OPIC the Olkaria III Power Plant [Member]
Non-Recourse Debt	192,646	210,641
Platanares Loan - OPIC [Member]
Non-Recourse Debt	104,459	112,652
Loan Agreement with Banco Industrial S.A. and Westrust Bank (International) Limited [Member]
Non-Recourse Debt	26,250	29,750
Plumstriker Loan Agreement [Member]
Non-Recourse Debt	21,615	0
Other Loans, Limited Resource [Member]
Non-Recourse Debt	8,367	0
Limited Resource	88,840	96,482
OrCal Geothermal Inc [Member]
Non-Recourse Debt		18,652
Don A. Campbell 1 ("DAC1") [Member]
Non-Recourse Debt	78,247	83,319
Ormat Funding Corp [Member]
Limited Resource	203,040	217,810
Senior Unsecured Bonds [Member]
Recourse Debt	204,332	204,332
Migdal Loan [Member]
Recourse Debt	150,000	100,000
Olkaria III DEG [Member]
Recourse Debt	79,632	47,500
Revolving Credit Lines With Banks [Member]
Recourse Debt	$ 40,550	$ 159,000