INCOME TAXES - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010
Reconciliation of Statutory Federal Tax Rate [Line Items]
Effective tax rate	13.80%	57.00%	63.10%	53.80%
Federal statutory rate	35.00%	35.00%	35.00%	35.00%
Maximum | ISRAEL | Ormat Systems Ltd | First benefited investment
Reconciliation of Statutory Federal Tax Rate [Line Items]
Income Tax Rate			25.00%
Maximum | ISRAEL | Ormat Systems Ltd | Second benefited investment
Reconciliation of Statutory Federal Tax Rate [Line Items]
Income Tax Rate			25.00%
ISRAEL | Ormat Systems Ltd
Reconciliation of Statutory Federal Tax Rate [Line Items]
Effective Income Tax Rate, Year One and Year two			15.00%
Effective Income Tax Rate, Year Three and Year Four			12.50%
Effective Income Tax Rate, Year Five and Thereafter			12.00%
Reduction in deferred taxes due to change in tax law			$ 0.5
ISRAEL | Ormat Systems Ltd | First benefited investment
Reconciliation of Statutory Federal Tax Rate [Line Items]
Income tax exemption period	2Y		2Y
Additional reduced income tax period	5Y		5Y
ISRAEL | Ormat Systems Ltd | Second benefited investment
Reconciliation of Statutory Federal Tax Rate [Line Items]
Income tax exemption period	2Y		2Y
Additional reduced income tax period	5Y		5Y