|
Variable Interest Entities and Unconsolidated Investments (VIE Texuals) (Details)
|
3 Months Ended | 6 Months Ended | 3 Months Ended | 6 Months Ended | 3 Months Ended | 6 Months Ended | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
|
Jun. 30, 2013
USD ($)
MW
|
Jun. 30, 2012
USD ($)
|
Jun. 30, 2013
USD ($)
MW
|
Jun. 30, 2012
USD ($)
|
Dec. 31, 2012
USD ($)
MW
|
Jun. 30, 2013
Greenfield [Member]
USD ($)
|
Jun. 30, 2012
Greenfield [Member]
USD ($)
|
Jun. 30, 2013
Greenfield [Member]
USD ($)
|
Jun. 30, 2012
Greenfield [Member]
USD ($)
|
Jun. 30, 2013
Greenfield [Member]
CAD
MW
|
Jun. 30, 2013
Whitby [Member]
USD ($)
MW
|
Jun. 30, 2012
Whitby [Member]
USD ($)
|
Jun. 30, 2013
Whitby [Member]
USD ($)
MW
|
Jun. 30, 2012
Whitby [Member]
USD ($)
|
Jun. 30, 2013
Inland Empire Energy Center [Member]
Y
MW
|
Jun. 30, 2013
Inland Empire Energy Center [Member]
Minimum [Member]
Y
|
Jun. 30, 2013
Inland Empire Energy Center [Member]
Maximum [Member]
Y
|
|
| Variable Interest Entity [Line Items] | |||||||||||||||||
| Power generation capacity | 9,027 | 9,027 | 8,255 | 1,038 | 50 | 50 | 775 | ||||||||||
| Variable Interest Entity, Financial or Other Support, Amount | $ 0 | $ 0 | $ 0 | $ 0 | |||||||||||||
| Equity Method Investment, Ownership Percentage | 50.00% | 50.00% | 50.00% | ||||||||||||||
| Equity Method Investment, Summarized Financial Information, Debt | 412,000,000 | 412,000,000 | 448,000,000 | ||||||||||||||
| Prorata Share of Equity Method Investment, Summarized Financial Information, Debt | 206,000,000 | 206,000,000 | 224,000,000 | ||||||||||||||
| Equity Method Investment, Summarized Financial Information, Term Loan Period | 18 years | ||||||||||||||||
| Equity Method Investment, Summarized Financial Information, Term Loan | 648,000,000 | ||||||||||||||||
| Distribution from equity method investee | $ 7,000,000 | $ 9,000,000 | $ 7,000,000 | $ 9,000,000 | $ 9,000,000 | $ 7,000,000 | $ 9,000,000 | $ 7,000,000 | |||||||||
| Call Option Exercise Period | 2,017 | 2,024 | |||||||||||||||
| Put Option Exercise Period | 2,025 | ||||||||||||||||