Note 4 - Investment in an Unconsolidated Company - Unconsolidated Investments Mainly in Power Plants (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Sarulla	$ (8,522)	$ (6,416)
Sarulla [Member]
Sarulla	$ 67,739	$ 34,084

Represents the accumulated losses in excess of investments in an entity not consolidated.

No definition available.

Name:	ora_AccumulatedLossesOfUnconsolidatedCompanyInExcessOfInvestment
Namespace Prefix:	ora_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant