Industry Segments (Details) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015 USD ($)	Jun. 30, 2014 USD ($)	Jun. 30, 2015 USD ($) segment	Jun. 30, 2014 USD ($)
Industry Segments
Number of operating segments | segment			3
Segment Information
Net sales	$ 3,469	$ 5,133	$ 6,558	$ 10,101
Pretax operating profit (loss)	504	1,970	270	3,901
Income taxes	(324)	(809)	(305)	(1,603)
Discontinued operations, net	(4)	273	(7)	528
Less: Net income attributable to noncontrolling interest		(3)		(5)
Net income (loss) attributable to common stock	176	1,431	(42)	2,821
Pre-tax impairment of oil and gas properties			310
Other charges			14
Oil and Gas
Segment Information
Net sales			4,351	7,305
Pretax operating profit (loss)			89	3,486
Net income (loss) attributable to common stock			89	3,486
Chemical
Segment Information
Net sales			2,030	2,462
Pretax operating profit (loss)			275	269
Net income (loss) attributable to common stock			275	269
Midstream and Marketing
Segment Information
Net sales			491	780
Pretax operating profit (loss)			72	375
Less: Net income attributable to noncontrolling interest				(5)
Net income (loss) attributable to common stock			72	370
Operating segments | Oil and Gas
Segment Information
Net sales	2,342	3,703
Pretax operating profit (loss)	355	1,767
Net income (loss) attributable to common stock	355	1,767
Operating segments | Chemical
Segment Information
Net sales	1,030	1,242
Pretax operating profit (loss)	136	133
Net income (loss) attributable to common stock	136	133
Operating segments | Midstream and Marketing
Segment Information
Net sales	294	440
Pretax operating profit (loss)	87	211
Less: Net income attributable to noncontrolling interest		(3)
Net income (loss) attributable to common stock	87	208
Corporate and Eliminations
Segment Information
Net sales	(197)	(252)	(314)	(446)
Pretax operating profit (loss)	(74)	(141)	(166)	(229)
Income taxes	(324)	(809)	(305)	(1,603)
Discontinued operations, net	(4)	273	(7)	528
Net income (loss) attributable to common stock	$ (402)	$ (677)	$ (478)	$ (1,304)