Derivatives And Risk Management (Narratives) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012
Derivative [Line Items]
Accumulated other comprehensive income, net gain related to hedging activities	$ 9.3
Deferred income tax liability, accumulated other comprehensive income	6.2
Cash flow hedge after-tax net gain to be transferred from accumulated other comprehensive income to earnings during the next twelve months	9.3
Realized Gain From Settled Contracts	309.2	631.5
Interest Rate Swap [Member]
Derivative [Line Items]
Notional amount of derivatives	$ 170.0
Year 2014 [Member]
Derivative [Line Items]
Volume of Natural Gas Production (in Bcf), Basis Swaps Not Qualifying for Hedge Accounting Treatment	21,300,000,000
Volume of Natural Gas Production (in Bcf), Fixed Price Swaps Not Qualifying for Hedge Accounting Treatment	181,600,000,000
Year 2015 [Member]
Derivative [Line Items]
Volume of Natural Gas Production (in Bcf), Basis Swaps Not Qualifying for Hedge Accounting Treatment	900,000,000
Volume of Natural Gas Production (in Bcf), Call Options Not Qualifying for Hedge Accounting Treatment	199,800,000,000