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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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

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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

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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

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Namespace Prefix:	us-gaap_
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Period Type:	instant

- Details

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- Details

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- Details

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Note 7 - Fair Value of Financial Instruments - Fair Value of Financial Instruments (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Revolving lines of credit	$ 51.5
Deposits	15.6	14.4
Fair Value, Inputs, Level 1 [Member]
Revolving lines of credit
Deposits	15.6	14.4
Fair Value, Inputs, Level 2 [Member]
Revolving lines of credit	51.5
Deposits
Fair Value, Inputs, Level 3 [Member]
Revolving lines of credit
Deposits
Olkaria III OPIC [Member]
Loans	234.6	253.4
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	234.6	253.4
Olkaria III DEG [Member]
Loans		16.3
Olkaria III DEG [Member] \| Fair Value, Inputs, Level 1 [Member]
Loans
Olkaria III DEG [Member] \| Fair Value, Inputs, Level 2 [Member]
Loans
Olkaria III DEG [Member] \| Fair Value, Inputs, Level 3 [Member]
Loans		16.3
Olkaria IV Loan - DEG 2 [Member]
Loans	50.7	50.9
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	50.7	50.9
Amatitlan Loan [Member]
Loans	32.8	37.3
Amatitlan Loan [Member] \| Fair Value, Inputs, Level 1 [Member]
Loans
Amatitlan Loan [Member] \| Fair Value, Inputs, Level 2 [Member]
Loans	32.8	37.3
Amatitlan Loan [Member] \| Fair Value, Inputs, Level 3 [Member]
Loans
OrCal Geothermal Inc [Member]
Notes	34.2	37.4
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	34.2	37.4
OFC Two Senior Secured Notes [Member]
Notes	234.6	249.0
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	234.6	249.0
OFC Senior Secured Notes [Member]
Notes		17.0
OFC Senior Secured Notes [Member] \| Fair Value, Inputs, Level 1 [Member]
Notes
OFC Senior Secured Notes [Member] \| Fair Value, Inputs, Level 2 [Member]
Notes		17.0
OFC Senior Secured Notes [Member] \| Fair Value, Inputs, Level 3 [Member]
Notes
Don A. Campbell 1 ("DAC1") [Member]
Notes	85.5	88.9
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	85.5	88.9
Senior Unsecured Bonds [Member]
Senior Unsecured Bonds	200.3	200.1
Senior Unsecured Bonds [Member] \| Fair Value, Inputs, Level 1 [Member]
Senior Unsecured Bonds
Senior Unsecured Bonds [Member] \| Fair Value, Inputs, Level 2 [Member]
Senior Unsecured Bonds
Senior Unsecured Bonds [Member] \| Fair Value, Inputs, Level 3 [Member]
Senior Unsecured Bonds	200.3	200.1
Other Long-term Debt [Member]
Other long-term debt	7.0	10.4
Other Long-term Debt [Member] \| Fair Value, Inputs, Level 1 [Member]
Other long-term debt
Other Long-term Debt [Member] \| Fair Value, Inputs, Level 2 [Member]
Other long-term debt		3.3
Other Long-term Debt [Member] \| Fair Value, Inputs, Level 3 [Member]
Other long-term debt	$ 7.0	$ 7.1