Derivative Financial Instruments (Schedule Of Derivative Financial Instruments Included In The Consolidated Balance Sheets And Consolidated Statement Of Operations) (Details) (USD $) In Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010	Dec. 31, 2010
Fair value of derivative assets	$ 432		$ 432		$ 389
Fair value of derivative liabilities	161		161		192
Total cash settlements	64	256	166	368
Total unrealized gains (losses)	327	(292)	74	231
Net gain (loss) recognized on statement of operations	391	(36)	240	599
Oil, Gas and NGL Derivatives [Member] | Commodity Derivatives [Member]
Total cash settlements	59	252	145	348
Total unrealized gains (losses)	357	(207)	103	317
Interest Rate And Other Financial Instruments [Member] | Interest Rate Derivatives [Member]
Total cash settlements	5	4	21	20
Total unrealized gains (losses)	(30)	(85)	(29)	(86)
Commodity Derivatives [Member] | Other Current Assets [Member]
Fair value of derivative assets	240		240		248
Commodity Derivatives [Member] | Other Long-Term Assets [Member]
Fair value of derivative assets	81		81		1
Commodity Derivatives [Member] | Other Current Liabilities [Member]
Fair value of derivative liabilities	83		83		50
Commodity Derivatives [Member] | Other Long-Term Liabilities [Member]
Fair value of derivative liabilities	78		78		142
Interest Rate Derivatives [Member] | Other Current Assets [Member]
Fair value of derivative assets	78		78		100
Interest Rate Derivatives [Member] | Other Long-Term Assets [Member]
Fair value of derivative assets	$ 33		$ 33		$ 40