Note 5 - Investment in an Unconsolidated Company - Unrealized Gain (Loss) on Derivative Instruments (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017
Interest Rate Swap [Member] \| Sarulla [Member]
Change, net of deferred tax, in unrealized gains (losses) in respect of the Company’s share in derivative instruments of unconsolidated investment	$ 2,235	$ 804

The entity's proportionate share for the period of the other comprehensive income (loss) of its investee (such as unconsolidated subsidiaries and joint ventures) to which the equity method of accounting is applied. This item represents after tax unrealized gains (loss) recognized during the period.

No definition available.

Name:	ora_OtherComprehensiveIncomeLossFromEquityMethodInvestmentsUnrealizedGainsLossesOnDerivativeInstrumentsNetOfTax
Namespace Prefix:	ora_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration