|
Derivative Instruments (Details) (USD $)
In Millions, unless otherwise specified |
9 Months Ended | 12 Months Ended |
|---|---|---|
|
Sep. 30, 2014
MWh
|
Dec. 31, 2013
MWh
|
|
|
Power [Member]
|
||
| Derivative [Line Items] | ||
| Derivative, Nonmonetary Notional Amount, Energy Measure | (57) | (29) |
|
Natural Gas [Member]
|
||
| Derivative [Line Items] | ||
| Derivative, Nonmonetary Notional Amount, Energy Measure | 230 | 448 |
|
Environmental Credits [Member]
|
||
| Derivative [Line Items] | ||
| Derivative, Nonmonetary Notional Amount, Mass | 2 | 0 |
|
Interest Rate Swap [Member]
|
||
| Derivative [Line Items] | ||
| Derivative, Notional Amount | $ 1,500 | $ 1,527 |