Note 22 - Commitments and Contingencies (Details Textual) - USD ($) $ in Millions		12 Months Ended
	Mar. 29, 2016	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Letters of Credit Outstanding, Amount		$ 213.8
Recorded Unconditional Purchase Obligation, Total		185.0
Royalty Cap Amount		2.1	$ 2.0
Royalty Cap Amount LIBOR Rate		$ 1.1	1.0
Former Local Sales Representative vs. Ormat [Member] | Pending Litigation [Member]
Loss Contingency, Damages Sought, Value	$ 4.6
Loss Contingency, Additional Damages Sought for Ormat Geothermal Products Sales in Chile, Percent	3.75%
Loss Contingency, Damages Sought, Ormat Geothermal Products Sales in Chile, Period	10 years
Minimum [Member]
Percentage For Royalty To Be Paid		3.50%
Maximum [Member]
Percentage For Royalty To Be Paid		5.00%
Construction In Process [Member]
Recorded Unconditional Purchase Obligation, Total		$ 59.5
Geothermal Resource Agreement [Member]
Royalty Expense		$ 21.7	$ 21.6	$ 19.4