Derivative Financial Instruments (Schedule Of Derivative Instruments) (Details) - USD ($) $ in Millions	Jun. 30, 2015	Dec. 31, 2014
Derivative [Line Items]
Derivative Assets, Current	$ 354	$ 578
Derivative Assets, Noncurrent	89	181
Derivative Liabilities, Current	0	3
Derivative Liabilities, Noncurrent	1	2
Not Designated as Hedging Instrument [Member]
Derivative [Line Items]
Derivative Asset, Fair Value, Net	443	759
Derivative Liability, Fair Value, Net	1	5
Not Designated as Hedging Instrument [Member] | Commodity Price Derivatives [Member] | Derivatives - Current [Member]
Derivative [Line Items]
Total derivatives, Asset, Gross	357	579
Derivative Liability, Fair Value, Gross Liability	3	1
Derivative Assets Offset In Balance Sheet	(3)	(1)
Derivative Liabilities Offset In Balance Sheet	(3)	(1)
Derivative Assets, Current	354	578
Derivative Liabilities, Current	0	0
Not Designated as Hedging Instrument [Member] | Commodity Price Derivatives [Member] | Derivatives - Noncurrent [Member]
Derivative [Line Items]
Total derivatives, Asset, Gross	95	182
Derivative Liability, Fair Value, Gross Liability	7	3
Derivative Assets Offset In Balance Sheet	(6)	(1)
Derivative Liabilities Offset In Balance Sheet	(6)	(1)
Derivative Assets, Noncurrent	89	181
Derivative Liabilities, Noncurrent	$ 1	2
Not Designated as Hedging Instrument [Member] | Interest Rate Derivatives [Member] | Derivatives - Current [Member]
Derivative [Line Items]
Derivative Liability, Fair Value, Gross Liability		3
Derivative Liabilities Offset In Balance Sheet		0
Derivative Liabilities, Current		$ 3