v2.4.0.8

Risk Management Activities (Commodity Price Risk Program Derivative Contracted Gross Volumes) (Details) | 6 Months Ended | 12 Months Ended
--- | --- | ---
Jun. 30, 2013 | Dec. 31, 2012
Gas Price Volatility Program [Member] |  |  |  |
Derivative [Line Items] |  |  |  |
Commodity price risk program derivative contracted gross volumes, MMDth | 23,900,000 |  | 26,300,000 |
Price Protection Service Program [Member] |  |  |  |
Derivative [Line Items] |  |  |  |
Commodity price risk program derivative contracted gross volumes, MMDth | 700,000 |  | 1,200,000 |
DependaBill Program [Member] |  |  |  |
Derivative [Line Items] |  |  |  |
Commodity price risk program derivative contracted gross volumes, MMDth | 200,000 |  | 300,000 |
Gas Marketing Program [Member] |  |  |  |
Derivative [Line Items] |  |  |  |
Commodity price risk program derivative contracted gross volumes, MMDth | 3,900,000 | [1] | 9,100,000 | [1]
Basis contract volumes, MMDth | 3,500,000 |  | 8,200,000 |
Gas Marketing Forward Physical Derivatives [Member] |  |  |  |
Derivative [Line Items] |  |  |  |
Commodity price risk program derivative contracted gross volumes, MMDth | 3,800,000 | [2] | 8,400,000 | [2]
Basis contract volumes, MMDth | 4,000,000 |  | 9,200,000 |
Electric Energy Program [Member] |  |  |  |
Derivative [Line Items] |  |  |  |
Commodity price risk program derivative contracted gross volumes, MMDth | 3,026,700,000 |  | 8,927,300,000 |
[1] | Basis contract volumes not included in the above table were 3.5 MMDth and 8.2 MMDth as of June 30, 2013 and December 31, 2012, respectively.
[2] | Basis contract volumes not included in the above table were 4.0 MMDth and 9.2 MMDth as of June 30, 2013 and December 31, 2012, respectively.

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