Acquisitions And Divestitures (Narrative) (Details) $ in Millions				3 Months Ended
	Apr. 15, 2016 USD ($)	Mar. 31, 2016 USD ($)	Jan. 07, 2016 USD ($) a	Mar. 31, 2016 USD ($)	Mar. 31, 2015 USD ($)
Business Acquisition [Line Items]
Proceeds from property and equipment divestitures				$ 18	$ 2
Installment Payment, Current [Member]
Business Acquisition [Line Items]
Installment payment		$ 229		229
Subsequent Event [Member] | Mississippian Assets [Member] | Forecast [Member]
Business Acquisition [Line Items]
Proceeds from property and equipment divestitures	$ 200
STACK [Member]
Business Acquisition [Line Items]
Close date of acquisition		Jan. 07, 2016
Number of net acres acquired | a			80,000
Aggregate purchase price			$ 1,500
Unproved properties		$ 1,300		1,300
Proved properties		$ 200		200
Cash payment to acquire interest			830
STACK [Member] | Common Stock [Member] | Equity Issued in Business Combination [Member]
Business Acquisition [Line Items]
Equity units value			659
EnLink [Member] | Equity Issued in Business Combination [Member]
Business Acquisition [Line Items]
Equity units value					$ 360
EnLink [Member] | Anadarko Basin [Member]
Business Acquisition [Line Items]
Close date of acquisition		Jan. 07, 2016
Aggregate purchase price			1,500
Cash payment to acquire interest			800
Amount committed to pay			$ 500
Deferred installment payment		$ 250		250
Commitment to pay cash due date			1 year
Intangible assets		1,000		1,000
Property and equipment		420		420
EnLink [Member] | Anadarko Basin [Member] | Installment Payment, Noncurrent [Member]
Business Acquisition [Line Items]
Deferred installment payment			$ 250
Commitment to pay cash due date			24 months
EnLink [Member] | Anadarko Basin [Member] | Installment Payment, Current [Member] | Undiscounted [Member]
Business Acquisition [Line Items]
Installment payment		$ 250		$ 250
General Partner [Member] | Anadarko Basin [Member] | Common Stock [Member] | Equity Issued in Business Combination [Member]
Business Acquisition [Line Items]
Equity units value			$ 215