Derivatives And Risk Management (Narrative) (Details) (USD $) In Millions, unless otherwise specified	6 Months Ended
	Jun. 30, 2014
Derivative [Line Items]
Accumulated other comprehensive income, net gain related to hedging activities	$ 1.0
Deferred income tax liability, accumulated other comprehensive income	1.0
Cash flow hedge after-tax net loss to be transferred from accumulated other comprehensive income to earnings during the next twelve months	(8.0)
Year 2014 [Member] | Fixed Price Swaps [Member]
Derivative [Line Items]
Volume of natural gas production	233,000,000,000
Year 2015 [Member] | Fixed Price Swaps [Member]
Derivative [Line Items]
Volume of natural gas production	240,000,000,000
Designated as Hedging Instrument [Member] | Year 2014 [Member] | Fixed Price Swaps [Member]
Derivative [Line Items]
Volume of natural gas production	142,000,000,000
Designated as Hedging Instrument [Member] | Year 2015 [Member] | Fixed Price Swaps [Member]
Derivative [Line Items]
Volume of natural gas production	120,000,000,000
Not Designated as Hedging Instrument [Member] | Interest Rate Swaps [Member]
Derivative [Line Items]
Notional amount	$ 170
Not Designated as Hedging Instrument [Member] | Year 2014 [Member] | Basis Swaps [Member]
Derivative [Line Items]
Volume of natural gas production	17,000,000,000
Not Designated as Hedging Instrument [Member] | Year 2014 [Member] | Fixed Price Swaps [Member]
Derivative [Line Items]
Volume of natural gas production	91,000,000,000
Not Designated as Hedging Instrument [Member] | Year 2015 [Member] | Basis Swaps [Member]
Derivative [Line Items]
Volume of natural gas production	15,000,000,000
Not Designated as Hedging Instrument [Member] | Year 2015 [Member] | Fixed Price Call Options [Member]
Derivative [Line Items]
Volume of natural gas production	200,000,000,000
Not Designated as Hedging Instrument [Member] | Year 2015 [Member] | Fixed Price Swaps [Member]
Derivative [Line Items]
Volume of natural gas production	120,000,000,000
Not Designated as Hedging Instrument [Member] | Year 2016 [Member] | Basis Swaps [Member]
Derivative [Line Items]
Volume of natural gas production	4,000,000,000
Not Designated as Hedging Instrument [Member] | Year 2016 [Member] | Fixed Price Call Options [Member]
Derivative [Line Items]
Volume of natural gas production	120,000,000,000