Derivative Financial Instruments (Schedule Of Derivative Financial Instruments Included In The Consolidated Balance Sheets) (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Derivatives, Fair Value [Line Items]
Fair value of derivative assets	$ 1,717	$ 2,004
Fair value of derivative liabilities	58	57
Oil, Gas And NGL Commodity Derivatives [Member] | Derivatives, At Fair Value [Member]
Derivatives, Fair Value [Line Items]
Fair value of derivative assets	1,668	1,967
Oil, Gas And NGL Commodity Derivatives [Member] | Other Long-Term Assets [Member]
Derivatives, Fair Value [Line Items]
Fair value of derivative assets	2	1
Oil, Gas And NGL Commodity Derivatives [Member] | Other Current Liabilities [Member]
Derivatives, Fair Value [Line Items]
Fair value of derivative liabilities	45	25
Oil, Gas And NGL Commodity Derivatives [Member] | Other Long-Term Liabilities [Member]
Derivatives, Fair Value [Line Items]
Fair value of derivative liabilities	7	26
Midstream Commodity Derivatives [Member] | Derivatives, At Fair Value [Member]
Derivatives, Fair Value [Line Items]
Fair value of derivative assets	14	17
Midstream Commodity Derivatives [Member] | Other Long-Term Assets [Member]
Derivatives, Fair Value [Line Items]
Fair value of derivative assets	8	10
Midstream Commodity Derivatives [Member] | Other Current Liabilities [Member]
Derivatives, Fair Value [Line Items]
Fair value of derivative liabilities	3	3
Midstream Commodity Derivatives [Member] | Other Long-Term Liabilities [Member]
Derivatives, Fair Value [Line Items]
Fair value of derivative liabilities	2	2
Interest Rate Derivatives [Member] | Derivatives, At Fair Value [Member]
Derivatives, Fair Value [Line Items]
Fair value of derivative assets	2	1
Interest Rate Derivatives [Member] | Other Long-Term Assets [Member]
Derivatives, Fair Value [Line Items]
Fair value of derivative assets	1
Interest Rate Derivatives [Member] | Other Current Liabilities [Member]
Derivatives, Fair Value [Line Items]
Fair value of derivative liabilities	1	1
Foreign Currency Derivatives [Member] | Derivatives, At Fair Value [Member]
Derivatives, Fair Value [Line Items]
Fair value of derivative assets	$ 22	$ 8