|
Variable Interest Entities and Unconsolidated Investments in Power Plants (Unconsolidated VIEs) (Details) (USD $)
In Millions, unless otherwise specified |
Jun. 30, 2014
|
Dec. 31, 2013
|
|---|---|---|
| Schedule of Equity Method Investments [Line Items] | ||
| Equity Method Investments | $ 92 | $ 93 |
|
Greenfield [Member]
|
||
| Schedule of Equity Method Investments [Line Items] | ||
| Equity Method Investments | 80 | 76 |
| Equity Method Investment, Ownership Percentage | 50.00% | |
|
Whitby [Member]
|
||
| Schedule of Equity Method Investments [Line Items] | ||
| Equity Method Investments | $ 12 | $ 17 |
| Equity Method Investment, Ownership Percentage | 50.00% |