Note 5 - Fair Value of Financial Instruments (Details) - Fair Value of Financial Instruments (USD $) In Millions, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Note 5 - Fair Value of Financial Instruments (Details) - Fair Value of Financial Instruments [Line Items]
Fair value levels-secured,unsecured and long term debt	$ 21.7	$ 23.3
Revolving credit lines with banks	97.2	112.0
Deposits	21.1	21.3
Olkaria III - DEG [Member] | Fair Value, Inputs, Level 3 [Member]
Note 5 - Fair Value of Financial Instruments (Details) - Fair Value of Financial Instruments [Line Items]
Fair value levels-secured,unsecured and long term debt	40.7	40.3
Olkaria III - DEG [Member]
Note 5 - Fair Value of Financial Instruments (Details) - Fair Value of Financial Instruments [Line Items]
Fair value levels-secured,unsecured and long term debt	40.7	40.3
Olkaria III - OPIC [Member] | Fair Value, Inputs, Level 3 [Member]
Note 5 - Fair Value of Financial Instruments (Details) - Fair Value of Financial Instruments [Line Items]
Fair value levels-secured,unsecured and long term debt	280.6	279.6
Olkaria III - OPIC [Member]
Note 5 - Fair Value of Financial Instruments (Details) - Fair Value of Financial Instruments [Line Items]
Fair value levels-secured,unsecured and long term debt	280.6	279.6
Amatitlan Member | Fair Value, Inputs, Level 3 [Member]
Note 5 - Fair Value of Financial Instruments (Details) - Fair Value of Financial Instruments [Line Items]
Fair value levels-secured,unsecured and long term debt	33.7	34.8
Amatitlan Member
Note 5 - Fair Value of Financial Instruments (Details) - Fair Value of Financial Instruments [Line Items]
Fair value levels-secured,unsecured and long term debt	33.7	34.8
Ormat Funding Corp [Member] | Fair Value, Inputs, Level 2 [Member]
Note 5 - Fair Value of Financial Instruments (Details) - Fair Value of Financial Instruments [Line Items]
Fair value levels-secured,unsecured and long term debt	74.9	83.5
Ormat Funding Corp [Member]
Note 5 - Fair Value of Financial Instruments (Details) - Fair Value of Financial Instruments [Line Items]
Fair value levels-secured,unsecured and long term debt	74.9	83.5
Orcal Geothermal Inc [Member] | Fair Value, Inputs, Level 3 [Member]
Note 5 - Fair Value of Financial Instruments (Details) - Fair Value of Financial Instruments [Line Items]
Fair value levels-secured,unsecured and long term debt	67.1	65.8
Orcal Geothermal Inc [Member]
Note 5 - Fair Value of Financial Instruments (Details) - Fair Value of Financial Instruments [Line Items]
Fair value levels-secured,unsecured and long term debt	67.1	65.8
OFC Two Senior Secured Notes [Member] | Fair Value, Inputs, Level 3 [Member]
Note 5 - Fair Value of Financial Instruments (Details) - Fair Value of Financial Instruments [Line Items]
Fair value levels-secured,unsecured and long term debt	119.1	119.0
OFC Two Senior Secured Notes [Member]
Note 5 - Fair Value of Financial Instruments (Details) - Fair Value of Financial Instruments [Line Items]
Fair value levels-secured,unsecured and long term debt	119.1	119.0
Senior Unsecured Bonds Member | Fair Value, Inputs, Level 3 [Member]
Note 5 - Fair Value of Financial Instruments (Details) - Fair Value of Financial Instruments [Line Items]
Fair value levels-secured,unsecured and long term debt	265.9	270.6
Senior Unsecured Bonds Member
Note 5 - Fair Value of Financial Instruments (Details) - Fair Value of Financial Instruments [Line Items]
Fair value levels-secured,unsecured and long term debt	265.9	270.6
Institutional Investors [Member] | Fair Value, Inputs, Level 3 [Member]
Note 5 - Fair Value of Financial Instruments (Details) - Fair Value of Financial Instruments [Line Items]
Fair value levels-secured,unsecured and long term debt	18.2	20.1
Institutional Investors [Member]
Note 5 - Fair Value of Financial Instruments (Details) - Fair Value of Financial Instruments [Line Items]
Fair value levels-secured,unsecured and long term debt	18.2	20.1
Fair Value, Inputs, Level 1 [Member]
Note 5 - Fair Value of Financial Instruments (Details) - Fair Value of Financial Instruments [Line Items]
Deposits	21.1	21.3
Fair Value, Inputs, Level 2 [Member]
Note 5 - Fair Value of Financial Instruments (Details) - Fair Value of Financial Instruments [Line Items]
Fair value levels-secured,unsecured and long term debt	21.7	23.3
Revolving credit lines with banks	$ 97.2	$ 112.0