Note 23 - Commitments and Contingencies (Details Textual) - USD ($)				1 Months Ended	12 Months Ended
	Oct. 26, 2016	Mar. 29, 2016	May 21, 2014	Jan. 31, 2014	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2003
Royalty Expense					$ 0	$ 0	$ 0
Letters of Credit Outstanding, Amount					341,600,000
Letter Of Credit Fair Value Disclosure					0
Recorded Unconditional Purchase Obligation					108,100,000
Royalty Cap Amount					1,800,000	1,700,000
Royalty Cap Amount LIBOR Rate					800,000	800,000
Operating Leases, Rent Expense					400,000	$ 400,000	300,000
Capital Leased Assets, Gross					6,900,000
Capital Lease, Period of Payments						5 years
Tax Abatement, Period			20 years
McGinness Plant[Member]
Tax Abatement Benefit, Value			$ 18,600,000
Tuscorura Plant [Member]
Tax Abatement Benefit, Value			$ 6,200,000
Two Former Employees Vs. Ormat [Member] | Settled Litigation [Member]
Loss Contingency, Damages Sought, Value				$ 375,000,000
Payments for Legal Settlements	$ 11,000,000
Two Former Employees Vs. Ormat [Member] | Settled Litigation [Member] | General and Administrative Expense [Member]
Litigation Settlement, Amount					11,000,000
Former Local Sales Representative vs. Ormat [Member] | Pending Litigation [Member]
Loss Contingency, Damages Sought, Value		$ 4,600,000
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					51,000,000
Geothermal Resource Agreement [Member]
Royalty Expense					$ 17,100,000	$ 15,400,000	$ 16,300,000