Industry Segments (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012 Segment	Sep. 30, 2011 Segment	Sep. 30, 2012 Segment	Sep. 30, 2011 Segment
Industry Segments
Number of reportable segments	3	3	3	3
Segment Information
Net sales	$ 5,965	$ 6,006	$ 18,001	$ 17,905
Pretax operating profit (loss)	2,234	2,862	7,140	8,251
Income taxes	(855)	(1,087)	(2,869)	(3,252)
Discontinued operations, net	(4)	(4)	(9)	138
Net income (loss)	1,375	1,771	4,262	5,137
Oil and Gas
Segment Information
Net sales	4,635	4,677	14,032	13,635
Pretax operating profit (loss)	2,026	2,612	6,573	7,704
Net income (loss)	2,026	2,612	6,573	7,704
Chemical
Segment Information
Net sales	1,119	1,231	3,439	3,721
Pretax operating profit (loss)	162	245	540	717
Net income (loss)	162	245	540	717
Midstream, Marketing and Other
Segment Information
Net sales	389	256	1,044	1,109
Pretax operating profit (loss)	156	77	364	378
Net income (loss)	156	77	364	378
Corporate and Eliminations
Segment Information
Net sales	(178)	(158)	(514)	(560)
Pretax operating profit (loss)	(110)	(72)	(337)	(548)
Income taxes	(855)	(1,087)	(2,869)	(3,252)
Discontinued operations, net	(4)	(4)	(9)	138
Net income (loss)	(969)	(1,163)	(3,215)	(3,662)
Charges on debt extinguishment				$ (163)