v2.4.0.6

Variable Interest Entities and Unconsolidated Investments (Details 3) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2009	Dec. 31, 2011	Dec. 31, 2010
Variable Interest Entities and Unconsolidated Investments (Textuals) [Abstract]
Equity Method Investment, Summarized Financial Information, Debt		$ 462	$ 494
Prorata Share of Equity Method Investment, Summarized Financial Information, Debt		231	247
Power generation capacity		11,391	13,656
Revenues	256
Operating expenses	195
Income from operations	61
Interest (income) expense	2
Other (income) expense, net	5
Net income	54
Riverside and Otay Mesa [Member]
Variable Interest Entities and Unconsolidated Investments (Textuals) [Abstract]
Power generation capacity		1,211
Inland Empire Energy Center [Member]
Variable Interest Entities and Unconsolidated Investments (Textuals) [Abstract]
Power generation capacity		775
Put Option Exercise Period		15
Minimum [Member] | Inland Empire Energy Center [Member]
Variable Interest Entities and Unconsolidated Investments (Textuals) [Abstract]
Call Option Exercise Period		7
Maximum [Member] | Inland Empire Energy Center [Member]
Variable Interest Entities and Unconsolidated Investments (Textuals) [Abstract]
Call Option Exercise Period		14
Greenfield [Member]
Variable Interest Entities and Unconsolidated Investments (Textuals) [Abstract]
Power generation capacity		1,038
Equity Method Investment, Summarized Financial Information, Term Loan Period		18
Equity Method Investment, Summarized Financial Information, Term Loan		$ 648
Project financing interest rate spread - Canadian LIBOR		1.125%
Project financing interest rate spread - Canadian Prime Rate		0.125%
Whitby [Member]
Variable Interest Entities and Unconsolidated Investments (Textuals) [Abstract]
Power generation capacity		50

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Equity Method Investment Summarized Financial Information Interest (Income) Expense

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Equity Method Investment Summarized Financial Information Other (Income) Expense Net

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Equity Method Investment, Summarized Financial Information, Term Loan

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Equity Method Investment, Summarized Financial Information, Term Loan Period

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Power generation capacity

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Project financing interest rate spread - Canadian LIBOR

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Project financing interest rate spread - Canadian Prime Rate

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Prorata Share of Equity Method Investment, Summarized Financial Information, Debt

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Put Option Exercise Period

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The amount of the cost of sales reported by an equity method investment of the entity.

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- Definition

The amount of gross profit (loss) reported by an equity method investment of the entity.

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

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The amount of net income (loss) reported by an equity method investment of the entity.

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The amount of revenue from sale of goods and services reduced by sales returns, allowances, and discounts reported by an equity method investment of the entity.

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