Acquisitions And Divestitures (Narrative) (Details) $ in Millions			1 Months Ended				6 Months Ended		12 Months Ended
	Dec. 22, 2014 USD ($) a	Dec. 19, 2014 USD ($)	May. 31, 2015 USD ($)	Apr. 30, 2015 USD ($) mi MMcf	Jan. 31, 2015 USD ($) a MMcf	Dec. 31, 2014 USD ($) item MMcf	Jun. 30, 2015	Sep. 30, 2014 USD ($) a	Dec. 31, 2014 USD ($) MMcf
Bridge Loan [Member]
Business Acquisition [Line Items]
Maturity date, month and year							2015-12
Bridge loan						$ 4,500			$ 4,500
Debt instrument, term						364 days			364 days
Debt issuance costs					$ 47
Unsecured Debt [Member] | Term Loan [Member]
Business Acquisition [Line Items]
Loans payable		$ 500				$ 500			$ 500
Maturity date, month and year							2016-12
Debt instrument, term		2 years
WPX Property Acquisition [Member]
Business Acquisition [Line Items]
Area of land purchased | a					46,700
Cash consideration					$ 270
Net production per day of acreage sold in MMcf | MMcf						50			50
Number of horizontal wells operated | item						63
Firm transportation capacity assumed, per day | MMcf					260
Allocated to natural gas and oil properties					$ 151
Allocated to intangible assets					$ 119
Statoil Property Acquisition [Member]
Business Acquisition [Line Items]
Area of land purchased | a					30,000
Allocated to natural gas and oil properties					$ 365
Percentage of interest acquired					20.00%
Cost to acquire property					$ 365
Chesapeake Property Acquisition [Member]
Business Acquisition [Line Items]
Area of land purchased | a	413,000
Cash consideration	$ 4,959
East Texas and Arkoma Basin [Member]
Business Acquisition [Line Items]
Proceeds from sale of oil and gas property and equipment			$ 214
Reduction in capitalized costs relating to proceeds			$ (206)
Bradford And Lycoming Counties, Pennsylvania [Member]
Business Acquisition [Line Items]
Proceeds from sale of oil and gas property and equipment				$ 489
Gain on sale of property				284
Net book value				$ 205
Number of miles of natural gas gathering pipeline | mi				100
Pipeline capacity per day | MMcf				600
Niobrara Formation In Colorado [Member]
Business Acquisition [Line Items]
Area of land purchased | a								380,000
Cost to acquire property								$ 215