Note 11 - Long-term Debt, Credit Agreements and Commercial Paper - Long-term Debt (Details) $ in Thousands, ₪ in Billions		12 Months Ended
		Dec. 31, 2020 USD ($)	Jul. 01, 2020 USD ($)	Jul. 01, 2020 ILS (₪)	May 13, 2020 USD ($)	Apr. 30, 2020 USD ($)	Apr. 20, 2020 USD ($)	Apr. 06, 2020 USD ($)	Dec. 31, 2019 USD ($)	Mar. 25, 2019 USD ($)	Mar. 22, 2018 USD ($)	Sep. 30, 2016 USD ($)	May 31, 2016 USD ($)	Jul. 31, 2015 USD ($)	Aug. 23, 2012 USD ($)
Limited Resource		$ 674,844							$ 732,461
Less current portion		(60,834)							(58,932)
Non current portion		614,010							673,529
Recourse Debt		799,330							474,514
Less current portion		(17,768)							(117,122)
Non current portion		781,562							357,392
Nonrecourse Debt [Member]
Amount Issued		147,500
Amount Outstanding		85,800
Senior Unsecured Bonds, Series 4 [Member]
Amount Issued		289,800	$ 289,800	₪ 1
Amount Outstanding		$ 311,000
Annual Interest Rate		3.35%
Maturity Date		Jun. 30, 2031
Other Loans, Limited and Non-recourse [Member]
Non-Recourse Debt		$ 9,826							8,997
Senior Unsecured Bonds, Series 3 [Member]
Amount Issued		218,000			$ 15,300		$ 14,500	$ 51,100				$ 137,000
Amount Outstanding		$ 218,000
Annual Interest Rate		4.45%						4.45%
Maturity Date		Sep. 30, 2022
Senior Unsecured Loan (Migdal) [Member]
Recourse Debt		$ 200,000							150,000
Amount Issued		100,000									$ 100,000
Amount Outstanding		$ 100,000
Annual Interest Rate	[1]	4.80%
Maturity Date		Mar. 31, 2029
Olkaria IV Loan - DEG 2 [Member]
Amount Issued		$ 50,000
Amount Outstanding		$ 37,500
Annual Interest Rate	[2]	6.28%
Maturity Date		Jun. 30, 2028
Loan Agreement With OPIC the Olkaria III Power Plant [Member]
Non-Recourse Debt		$ 174,652							192,646
Amount Issued		310,000													$ 310,000
Amount Outstanding		174,700
Loan Agreement With OPIC the Olkaria III Power Plant [Member] | Tranche One [Member]
Amount Issued		85,000
Amount Outstanding		$ 47,200
Annual Interest Rate	[3]	6.34%
Maturity Date		Dec. 31, 2030
Loan Agreement With OPIC the Olkaria III Power Plant [Member] | Tranche Two [Member]
Amount Issued		$ 180,000
Amount Outstanding		$ 100,600
Annual Interest Rate	[3]	6.29%
Maturity Date		Jun. 30, 2030
Loan Agreement With OPIC the Olkaria III Power Plant [Member] | Tranche Three [Member]
Amount Issued		$ 45,000
Amount Outstanding		$ 26,900
Annual Interest Rate	[3]	6.12%
Maturity Date		Dec. 31, 2030
Platanares Finance Agreement [Member]
Non-Recourse Debt		$ 96,266							104,459
Amount Issued		114,700
Amount Outstanding		$ 96,300
Annual Interest Rate	[3]	7.02%
Maturity Date		Sep. 30, 2032
Loan Agreement with Banco Industrial S.A. and Westrust Bank (International) Limited1 [Member]
Amount Issued		$ 42,000												$ 42,000
Amount Outstanding		$ 22,800
Maturity Date		Jun. 30, 2027
Loan Agreement with Banco Industrial S.A. and Westrust Bank (International) Limited1 [Member] | London Interbank Offered Rate (LIBOR) [Member]
Annual Interest Rate, Variable	[3]	4.35%
Plumstriker Loan Agreement [Member]
Non-Recourse Debt		$ 18,081							21,615
Amount Issued		23,500
Amount Outstanding		$ 18,100
Maturity Date		May 31, 2026
Plumstriker Loan Agreement [Member] | London Interbank Offered Rate (LIBOR) [Member]
Annual Interest Rate, Variable	[3]	3.50%
Don A. Campbell 1 ("DAC1") [Member]
Non-Recourse Debt		$ 73,121							78,247
Amount Issued		92,500
Amount Outstanding		$ 73,100
Annual Interest Rate	[3]	4.03%
Maturity Date		Sep. 30, 2033
Ormat Funding Corp [Member]
Limited Resource		$ 188,223							203,040
Amount Issued		291,700
Amount Outstanding		188,200
Ormat Funding Corp [Member] | Series A Senior Notes [Member]
Amount Issued		151,700
Amount Outstanding		$ 86,900
Annual Interest Rate	[4]	4.69%
Maturity Date		Dec. 31, 2032
Ormat Funding Corp [Member] | Series C Senior Notes [Member]
Amount Issued		$ 140,000
Amount Outstanding		$ 101,300
Annual Interest Rate	[4]	4.61%
Maturity Date		Dec. 31, 2032
Prudential Capital Group Agreement [Member]
Amount Issued													$ 20,000
Amount Outstanding		$ 16,000
Prudential Capital Group Agreement [Member] | Nonrecourse Debt [Member]
Amount Issued		20,000
Amount Outstanding		$ 17,500
Annual Interest Rate	[5]	5.80%
Maturity Date		Mar. 31, 2023
Additional Migdal Loan [Member]
Amount Issued		$ 50,000								$ 50,000
Amount Outstanding		$ 50,000
Annual Interest Rate	[1]	4.60%
Maturity Date		Mar. 31, 2029
Olkaria IV Loan - DEG 3 [Member]
Amount Issued		$ 41,500
Amount Outstanding		$ 32,800
Annual Interest Rate	[2]	6.04%
Maturity Date		Jun. 30, 2028
DOE Loan Guarantee [Member] | Nonrecourse Debt [Member]
Amount Issued		$ 96,800
Amount Outstanding		$ 42,000
Annual Interest Rate	[5]	2.60%
Maturity Date		Feb. 28, 2035
Second Addendum Migdal Loan [Member]
Amount Issued		$ 50,000				$ 50,000
Amount Outstanding		$ 50,000
Annual Interest Rate	[1]	5.44%
Maturity Date		Mar. 31, 2029
Prudential Capital Purchase Agreement [member] | Nonrecourse Debt [Member]
Amount Issued		$ 30,700
Amount Outstanding		$ 26,300
Annual Interest Rate	[5]	6.75%
Maturity Date		Dec. 31, 2037
Loan Agreement with Banco Industrial S.A. and Westrust Bank (International) Limited [Member]
Non-Recourse Debt		$ 22,750							26,250
Migdal Senior Unsecured Loan [Member]
Amount Issued		200,000
Amount Outstanding		200,000
Other Loans, Limited Resource [Member]
Non-Recourse Debt		7,807							8,367
Limited Resource		84,118							88,840
Senior Unsecured Bonds [Member]
Recourse Debt		529,066							204,332
Olkaria III DEG [Member]
Recourse Debt		70,264							79,632
Revolving Credit Lines With Banks [Member]
Recourse Debt		$ 0							$ 40,550

[1] payable semi-annually in arrears.

[2] payable semi-annually

[3] payable quarterly

[4] payable quarterly in arrears

[5] payable semi-annually, except for Nevada non-recourse which is payable quarterly