Other long term debt fair value disclosure.

No definition available.

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

- Definition

The aggregate of all deposit liabilities held by the entity, including foreign and domestic, interest and noninterest bearing; may include demand deposits, saving deposits, Negotiable Order of Withdrawal (NOW) and time deposits among others.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03.12)
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Fair value portion of contractual arrangement with a lender under which borrowings can be made up to a specific amount at any point in time.

+ References

No definition available.

+ Details

Name:	us-gaap_LinesOfCreditFairValueDisclosure
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Fair value portion of contractual obligation to pay money on demand or on fixed or determinable dates.

+ References

No definition available.

+ Details

Name:	us-gaap_LoansPayableFairValueDisclosure
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The fair value amount of long-term debt whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission.

+ References

No definition available.

+ Details

Name:	us-gaap_LongTermDebtFairValue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Fair value portion of notes payable.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.19,20,22)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

Name:	us-gaap_NotesPayableFairValueDisclosure
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Details

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- Details

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- Details

Name:	us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel3Member
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Data Type:	na
Balance Type:
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- Details

Name:	us-gaap_DebtInstrumentAxis=ora_OlkariaIIIOPICMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=ora_AmatitlanLoanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=ora_OrCalGeothermalIncMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=ora_OFCTwoSeniorSecuredNotesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=ora_DonACampbell1Dac1Member
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- Details

Name:	us-gaap_DebtInstrumentAxis=ora_SeniorUnsecuredBondsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=ora_SeniorUnsecuredLoanMember
Namespace Prefix:
Data Type:	na
Balance Type:
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- Details

Name:	us-gaap_DebtInstrumentAxis=ora_OtherLongtermDebtMember
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Note 5 - Fair Value of Financial Instruments - Fair Value of Financial Instruments (Details) - USD ($) $ in Millions	Mar. 31, 2018	Dec. 31, 2017
Revolving lines of credit	$ 38.5	$ 51.5
Deposits	15.2	15.6
Fair Value, Inputs, Level 1 [Member]
Revolving lines of credit
Deposits	15.2	15.6
Fair Value, Inputs, Level 2 [Member]
Revolving lines of credit	38.5	51.5
Deposits
Fair Value, Inputs, Level 3 [Member]
Revolving lines of credit
Deposits
Olkaria III OPIC [Member]
Loans	225.2	234.6
Olkaria III OPIC [Member] \| Fair Value, Inputs, Level 1 [Member]
Loans
Olkaria III OPIC [Member] \| Fair Value, Inputs, Level 2 [Member]
Loans
Olkaria III OPIC [Member] \| Fair Value, Inputs, Level 3 [Member]
Loans	225.2	234.6
Olkaria IV Loan - DEG 2 [Member]
Loans	50.6
Olkaria IV Loan - DEG 2 [Member] \| Fair Value, Inputs, Level 1 [Member]
Loans
Olkaria IV Loan - DEG 2 [Member] \| Fair Value, Inputs, Level 2 [Member]
Loans
Olkaria IV Loan - DEG 2 [Member] \| Fair Value, Inputs, Level 3 [Member]
Loans	50.6	50.7
Amatitlan Loan [Member]
Loans	31.2	32.8
Amatitlan Loan [Member] \| Fair Value, Inputs, Level 1 [Member]
Loans
Amatitlan Loan [Member] \| Fair Value, Inputs, Level 2 [Member]
Loans	31.2	32.8
Amatitlan Loan [Member] \| Fair Value, Inputs, Level 3 [Member]
Loans
OrCal Geothermal Inc [Member]
Notes	28.5	34.2
OrCal Geothermal Inc [Member] \| Fair Value, Inputs, Level 1 [Member]
Notes
OrCal Geothermal Inc [Member] \| Fair Value, Inputs, Level 2 [Member]
Notes
OrCal Geothermal Inc [Member] \| Fair Value, Inputs, Level 3 [Member]
Notes	28.5	34.2
OFC Two Senior Secured Notes [Member]
Notes	223.9	234.6
OFC Two Senior Secured Notes [Member] \| Fair Value, Inputs, Level 1 [Member]
Notes
OFC Two Senior Secured Notes [Member] \| Fair Value, Inputs, Level 2 [Member]
Notes
OFC Two Senior Secured Notes [Member] \| Fair Value, Inputs, Level 3 [Member]
Notes	223.9	234.6
Don A. Campbell 1 ("DAC1") [Member]
Notes	81.6	85.5
Don A. Campbell 1 ("DAC1") [Member] \| Fair Value, Inputs, Level 1 [Member]
Notes
Don A. Campbell 1 ("DAC1") [Member] \| Fair Value, Inputs, Level 2 [Member]
Notes
Don A. Campbell 1 ("DAC1") [Member] \| Fair Value, Inputs, Level 3 [Member]
Notes	81.6	85.5
Senior Unsecured Bonds [Member]
Senior secured debt	196.5	200.3
Senior Unsecured Bonds [Member] \| Fair Value, Inputs, Level 1 [Member]
Senior secured debt
Senior Unsecured Bonds [Member] \| Fair Value, Inputs, Level 2 [Member]
Senior secured debt
Senior Unsecured Bonds [Member] \| Fair Value, Inputs, Level 3 [Member]
Senior secured debt	196.5	200.3
Senior Unsecured Loan [Member]
Senior secured debt	100.7
Senior Unsecured Loan [Member] \| Fair Value, Inputs, Level 1 [Member]
Senior secured debt
Senior Unsecured Loan [Member] \| Fair Value, Inputs, Level 2 [Member]
Senior secured debt
Senior Unsecured Loan [Member] \| Fair Value, Inputs, Level 3 [Member]
Senior secured debt	100.7
Other Long-term Debt [Member]
Senior secured debt		7.0
Other long-term debt	6.6
Other Long-term Debt [Member] \| Fair Value, Inputs, Level 1 [Member]
Senior secured debt
Other long-term debt
Other Long-term Debt [Member] \| Fair Value, Inputs, Level 2 [Member]
Senior secured debt
Other long-term debt
Other Long-term Debt [Member] \| Fair Value, Inputs, Level 3 [Member]
Senior secured debt		$ 7.0
Other long-term debt	$ 6.6