v2.4.0.6

Related party transactions (Details) (USD $) In Millions, unless otherwise specified | 12 Months Ended |  |  |  |
--- | --- | --- | --- | --- | ---
Dec. 31, 2011 Idaho Wind | Dec. 31, 2010 Idaho Wind | Dec. 31, 2011 ArcLight | Dec. 31, 2010 ArcLight | Dec. 31, 2009 ArcLight item
Related party transactions |  |  |  |  |
Number of private equity funds |  |  |  |  | 2
Aggregate amount payable on termination of contract |  |  |  |  | $ 15.0
Payment due on termination date for termination of agreement |  |  |  |  | 6.0
Additional payment due on first anniversary of termination date |  |  |  | 5.0 |
Additional payment due on second anniversary of termination date |  |  | 3.0 |  |
Additional payment due on third anniversary of termination date |  |  | 1.0 |  |
Estimated fair value of termination fee due |  |  | 0.9 |  |
Loan to Idaho Wind |  | 22.8 |  |  |
Interest income from loan given to Idaho Wind | $ 1.6 |  |  |  |

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- Definition Represents the estimated fair value of remaining liability associated with the termination fees. + References No definition available. + Details
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- Definition Represents the additional payment due on second anniversary of the termination date. + References No definition available. + Details
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- Definition The aggregate amount of receivables to be collected from related parties where one party can exercise control or significant influence over another party; including affiliates, owners or officers and their immediate families, pension trusts, and so forth, at the financial statement date. which are usually due within one year (or one business cycle). + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 57 -Paragraph 2 -Subparagraph d -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 3 -Subparagraph a -Article 5 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.3(a)(2)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section 45 -Paragraph 1 -Subparagraph (d) -URI http://asc.fasb.org/extlink&oid=6361293&loc=d3e6676-107765 Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.4-08.(k)(1)) -URI http://asc.fasb.org/extlink&oid=6881521&loc=d3e23780-122690 Reference 6: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 850 -SubTopic 10 -Section 50 -Paragraph 1 -Subparagraph (d) -URI http://asc.fasb.org/extlink&oid=6457730&loc=d3e39549-107864 Reference 7: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 08 -Paragraph k -Subparagraph 2 -Article 4 + Details
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