Derivatives And Risk Management (Narrative) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014
Derivative [Line Items]
Accumulated other comprehensive income, net gain related to hedging activities	$ 98
Deferred income tax liability, accumulated other comprehensive income	65
Cash flow hedge after-tax net gain to be transferred from accumulated other comprehensive income to earnings during the next twelve months	98
Interest Rate Swaps [Member]
Derivative [Line Items]
Notional amount of derivatives	$ 170
Year 2015 [Member]
Derivative [Line Items]
Volume of natural gas production	240,000,000,000
Volume of Natural Gas Production (in Bcf), Basis Swaps Not Qualifying for Hedge Accounting Treatment	22,000,000,000
Year 2015 [Member] | Fixed Price Call Options [Member]
Derivative [Line Items]
Volume of Natural Gas Production (in Bcf), Call Options Not Qualifying for Hedge Accounting Treatment	200,000,000,000
Year 2015 [Member] | Fixed Price Swaps [Member]
Derivative [Line Items]
Volume of natural gas production	120,000,000,000
Volume of Natural Gas Production (in Bcf), Basis Swaps Not Qualifying for Hedge Accounting Treatment	120,000,000,000
Year 2016 [Member]
Derivative [Line Items]
Volume of Natural Gas Production (in Bcf), Basis Swaps Not Qualifying for Hedge Accounting Treatment	4,000,000,000
Year 2016 [Member] | Fixed Price Call Options [Member]
Derivative [Line Items]
Volume of Natural Gas Production (in Bcf), Fixed Price Swaps Not Qualifying for Hedge Accounting Treatment	120,000,000,000
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