Note 18 - Income Taxes (Details Textual) - USD ($) $ in Thousands					1 Months Ended		12 Months Ended
		Apr. 24, 2018	Jun. 20, 2017	Sep. 11, 2015	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Deferred Tax Assets, Investments					$ 813	$ 813					$ 813	$ 813
Deferred Tax Assets, Tax Credit Carryforwards, General Business					90,913	85,193					90,913	85,193
Deferred Tax Assets, Tax Credit Carryforwards, Foreign					58,072	86,206					58,072	86,206
Deferred Tax Assets, Valuation Allowance, Total					22,441	77,571					22,441	$ 77,571	$ 116,234	$ 92,898
Valuation Allowance, Deferred Tax Asset, Increase (Decrease), Amount											$ (55,100)
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent											21.00%	35.00%	35.00%
Provisional Tax Effect, 2017 Tax Cuts and Jobs Act, Impact on Income Tax Expense (Benefit)											$ 71,900
Final Tax Effect, 2017 Tax Cuts and Jobs Act, Impact on Income Tax Expense (Benefit)											64,200
Income Tax Expense (Benefit), Continuing Operations, Adjustment of Deferred Tax (Asset) Liability											(3,500)	$ 22,600
Uncertain Tax Benefit, Reudction to Deferred Tax Asset	[1]				95	95					95	95
Foreign Earnings Repatriated						300,000						396,000
Distribution of Earnings in Foreign Subsidiaries					96,000
Undistributed Earnings of Foreign Subsidiaries					211,300						211,300
Unrecognized Tax Benefits that Would Impact Effective Tax Rate					11,800	8,900					11,800	8,900
Unrecognized Tax Benefits, Reduction Resulting from Lapse of Applicable Statute of Limitations											$ 300	800	$ 5,400
Placed in Service After December 31, 2022 and Before January 1, 2024 [Member]
Depreciation Bonus Permitted Write Off Equipment Cost Percentage											80.00%
Placed in Service After December 31, 2023 and Before January 1, 2025 [Member]
Depreciation Bonus Permitted Write Off Equipment Cost Percentage											60.00%
Placed in Service After December 31, 2024 and Before January 1, 2026 [Member]
Depreciation Bonus Permitted Write Off Equipment Cost Percentage											40.00%
Placed in Service After December 31, 2025 and Before January 1, 2027 [Member]
Depreciation Bonus Permitted Write Off Equipment Cost Percentage											20.00%
Accounting Standards Update 2013-11 [Member]
Uncertain Tax Benefit, Reudction to Deferred Tax Asset						100						100
U.S. Geothermal [Member]
Business Acquisition, Percentage of Voting Interests Acquired		100.00%
Business Combination, Consideration Transferred, Total		$ 110,000
Business Combination Recognized Identifiable Assets Acquired and Liabilities Assumed, Deferred Tax Assets (Liabilities), Net		1,700
Business Combination Recognized Identifiable Assets Acquired and Liabilities Assumed, Deferred Tax Assets		1,700
Deferred Taxes, Business Combination, Valuation Allowance, Available to Reduce Deferred Tax Asset		2,100
Investment Tax Credit Carryforward [Member]
Deferred Tax Assets, Investments					800						$ 800
General Business Tax Credit Carryforward [Member]
Deferred Tax Assets, Tax Credit Carryforwards, General Business					90,900						$ 90,900
Tax Credit Carryforward Expiration Period											20 years
Minimum [Member] | General Business Tax Credit Carryforward [Member]
Tax Credit Carryforward Expiration Year											2026
Maximum [Member] | General Business Tax Credit Carryforward [Member]
Tax Credit Carryforward Expiration Year											2038
Domestic Tax Authority [Member]
Operating Loss Carryforwards, Total					230,500						$ 230,500
Operating Loss Carryforwards Expiring Amount					224,500						224,500
Operating Loss Carryforwards Available For Indefinite Period					6,000						$ 6,000
Domestic Tax Authority [Member] | Placed in Service Before January 2018 [Member]
Investment Tax Credit, Percentage of Eligible Cost											30.00%
Domestic Tax Authority [Member] | U.S. Geothermal [Member]
Business Combination Recognized Identifiable Assets Acquired and Liabilities Assumed, Deferred Tax Assets		115,200
Domestic Tax Authority [Member] | Minimum [Member]
Tax Credit Carryforward Expiration Year											2027
Domestic Tax Authority [Member] | Maximum [Member]
Tax Credit Carryforward Expiration Year											2037
State and Local Jurisdiction [Member]
Operating Loss Carryforwards, Total					269,100	$ 264,700					$ 269,100	$ 264,700
Operating Loss Carryforwards Available For Indefinite Period					3,300						$ 3,300
State and Local Jurisdiction [Member] | U.S. Geothermal [Member]
Business Combination Recognized Identifiable Assets Acquired and Liabilities Assumed, Deferred Tax Assets		$ 49,900
State and Local Jurisdiction [Member] | Minimum [Member]
Tax Credit Carryforward Expiration Year											2025
State and Local Jurisdiction [Member] | Maximum [Member]
Tax Credit Carryforward Expiration Year											2038
Foreign Tax Authority [Member]
Tax Credit Carryforward Expiration Period											10 years
Deferred Tax Assets, Tax Credit Carryforwards, Foreign					58,100						$ 58,100
Foreign Tax Authority [Member] | Israel Tax Authority [Member]
Foreign Earnings Repatriated											53,000
Foreign Income Tax Expense (Benefit), Continuing Operations, Total											14,400
Deferred Tax Liabilities, Gross, Total					8,100						8,100
Tax Credit Carryforward, Amount					$ 2,200						$ 2,200
National Corporate Tax Rate											23.00%	24.00%	25.00%	26.50%
Foreign Tax Authority [Member] | Israel Tax Authority [Member] | Ormat Systems Ltd [Member]
Effective Income Tax Rate, Year Four and Thereafter															16.00%
Tax Rate on Exempt Income, in Event of Distribution											25.00%
Deferred Tax Liability, Rate, Respect of Tax Exempt Income											25.00%
Foreign Tax Authority [Member] | Tax Authority of Guatemala in Guatemala [Member]
National Corporate Tax Rate											25.00%
Tax Exemption Period											10 years
Effective Income Tax Rate											7.00%
Effective Income Tax Rate Reconciliation, Tax Exempt Income, Amount											$ 2,000	$ 2,600	$ 3,300
Income Tax Benefit From Examination Per Share											0.04	0.05	0.07
Foreign Tax Authority [Member] | Kenya Revenue Authority [Member]
National Corporate Tax Rate											37.50%
Investment Deduction Percentage			150.00%	150.00%
Income Tax Examination, Penalties Paid			$ 2,600
Income Tax Examination, Interest Accrued and Waiver Requested			$ 1,200
Foreign Tax Authority [Member] | Ministry of the Economy, Finance and Industry, France [Member]
National Corporate Tax Rate												34.43%
Corporate Income Tax Rate, Taxable Income Exceeding Euro 0.5 Million											33.30%
Foreign Tax Authority [Member] | Ministry of the Economy, Finance and Industry, France [Member] | Scenario, Forecast [Member]
National Corporate Tax Rate							25.00%	26.50%	28.00%
Corporate Income Tax Rate, Taxable Income Exceeding Euro 0.5 Million										31.00%
Foreign Tax Authority [Member] | Sistema de Administración de Rentas [Member]
Income Taxes Exempt Period											10 years
Foreign Tax Authority [Member] | Inland Revenue Department, New Zealand [Member]
National Corporate Tax Rate														28.00%	28.00%	28.00%
Foreign Tax Authority [Member] | Minimum [Member]
Tax Credit Carryforward Expiration Year											2027
Foreign Tax Authority [Member] | Minimum [Member] | Kenya Revenue Authority [Member]
Tax Losses Carryforward Period											5 years
Foreign Tax Authority [Member] | Maximum [Member] | Kenya Revenue Authority [Member]
Tax Losses Carryforward Period											10 years

[1] The non-current deferred tax asset has been reduced by the uncertain tax benefit of $0.1 million in accordance with ASU 2013-11, Income Taxes.