Condensed Consolidated Statements Of Comprehensive Income (USD $) In Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010
Condensed Consolidated Statements Of Comprehensive Income [Abstract]
Net income	$ 922	$ 558	$ 1,269	$ 1,550
Other comprehensive income, net of income tax:
Change in fair value of derivative instruments, net of income taxes of $44 million, $39 million, $133 million and $153 million	72	65	218	251
Reclassification of gain on settled contracts, net of income taxes of ($49) million, ($68) million, ($88) million and ($203) million	(80)	(112)	(144)	(333)
Ineffective portion of derivatives qualifying for cash flow hedge accounting, net of income taxes of $2 million, ($2) million, ($5) million and $8 million	3	(3)	(8)	12
Unrealized gain (loss) on marketable securities, net of income taxes of ($1) million, $1 million, ($2) million and ($4) million	(1)	1	(4)	(7)
Comprehensive income	$ 916	$ 509	$ 1,331	$ 1,473