Risk Management Activities (Commodity Price Risk Program Derivative Contracted Gross Volumes) (Details)	6 Months Ended	12 Months Ended
	Jun. 30, 2014	Dec. 31, 2013
Gas Price Volatility Program [Member]
Derivative [Line Items]
Commodity price risk program derivative contracted gross volumes, MMDth	16,700,000	17,000,000
Price Protection Service Program [Member]
Derivative [Line Items]
Commodity price risk program derivative contracted gross volumes, MMDth	200,000	700,000
DependaBill Program [Member]
Derivative [Line Items]
Commodity price risk program derivative contracted gross volumes, MMDth	200,000	200,000
Electric Hedging Program [Member]
Derivative [Line Items]
Electric hedging program	100,000	0
Electric Energy Program [Member]
Derivative [Line Items]
Commodity Price Risk Program Derivative Contracted Gross Volumes, mw	4,700,000,000	1,248,000,000