Describes important rulings or decisions made by the judge, arbitrator or mediator in the legal matter that could impact the outcome of the case.

+ References+ Details

Describe actions taken by the defendant in the legal matter.

+ References+ Details

- Definition

Describes actions taken or threatened by the plaintiff in the legal matter.

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- Definition

The value (monetary amount) of the award the plaintiff seeks in the legal matter.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 450

-SubTopic 20

-Section 50

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6952336&loc=d3e14326-108349

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-Publisher FASB

-Name Accounting Standards Codification

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Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 5

-Paragraph 9

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 450

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-Section 50

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-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

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-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 6: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 5

-Paragraph 10

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 7: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 5

-Paragraph 12

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

+ Details

- Definition

States the date the complaint was formally filed in a court of law, in arbitration or mediation.

+ References+ Details

CONTINGENCIES - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2012 Securities Class Actions LegalMatter	Mar. 31, 2012 Securities Class Actions First Lawsuit	Mar. 31, 2012 Securities Class Actions Second Lawsuit	Mar. 31, 2012 Securities Class Actions Third Lawsuit	Mar. 31, 2012 Stockholder Derivative Cases LegalMatter	Mar. 31, 2012 Stockholder Derivative Cases For County Of Washoe LegalMatter	Mar. 31, 2012 Stockholder Derivative Cases For District Of Nevada LegalMatter	Mar. 31, 2012 Stockholder Derivative Cases For County Of Washoe First Lawsuit	Mar. 31, 2012 Stockholder Derivative Cases For County Of Washoe Second Lawsuit	Mar. 31, 2012 Stockholder Derivative Cases For District Of Nevada First Lawsuit	Mar. 31, 2012 Stockholder Derivative Cases For District Of Nevada Second Lawsuit	Jan. 04, 2012 Jurisdictional threshold North Brawley Project MW	Jan. 04, 2012 Jurisdictional threshold East Brawley Project MW
Loss Contingencies [Line Items]
Number of lawsuits filed		3				4	2	2
Lawsuit filing date			2010-03-09	2010-03-18	2010-04-07				2010-03-16	2010-04-21	2010-03-29	2010-06-07
Cash payment to be funded by the company if the proposed class action dismissed	$ 3.1
Descriptions of derivative cases filed							The two stockholder derivative cases filed in the Second Judicial District Court of the State of Nevada in and for the County of Washoe were consolidated by the Court in an order dated May 27, 2010	The two stockholder derivative cases filed in the United States District Court for the District of Nevada were consolidated by the Court in an order dated August 31, 2010
Descriptions of derivative cases filed by plaintiff							Plaintiffs filed a consolidated derivative complaint on September 7, 2010.	Plaintiffs filed a consolidated derivative complaint on October 28, 2010.
Descriptions of derivative cases filed by defendant							In accordance with a stipulation between the parties, defendants filed a motion to dismiss on November 16, 2010.	The Company filed a motion to dismiss on December 13, 2010.
Expected generating capacity													50	50