Segments - Schedule of Industry Segments and Eliminations (Details) shares in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2021 USD ($) site shares	Mar. 31, 2020 USD ($)
Segment Information
Number of operating segments | site	3
Net sales	$ 5,293	$ 6,613
Income (loss) from continuing operations before income taxes	315	(2,038)
Income tax benefit (expense)	(16)	25
Income (loss) from continuing operations	299	(2,013)
Gain (loss) on derivative instrument	399	(585)
Anadarko acquisition-related costs	41	148
Disposed of by Sale, Not Discontinued Operations | WES Midstream segment
Segment Information
Gain on sale	$ 102
Number of limited partner units sold (in units) | shares	11.5
Operating Segments | Oil and gas
Segment Information
Net sales	$ 3,664	5,060
Income (loss) from continuing operations before income taxes	(62)	236
Income tax benefit (expense)	0	0
Income (loss) from continuing operations	(62)	236
Impairment charge	135	317
Gain (loss) on derivative instrument		952
Asset impairments		264
Operating Segments | Chemical
Segment Information
Net sales	1,088	962
Income (loss) from continuing operations before income taxes	251	186
Income tax benefit (expense)	0	0
Income (loss) from continuing operations	251	186
Operating Segments | Midstream and marketing
Segment Information
Net sales	807	790
Income (loss) from continuing operations before income taxes	282	(1,287)
Income tax benefit (expense)	0	0
Income (loss) from continuing operations	282	(1,287)
Goodwill impairment	1,400
Operating Segments | Midstream and marketing | Disposed of by Sale, Not Discontinued Operations | WES Midstream segment
Segment Information
Gain on sale	$ 102
Number of limited partner units sold (in units) | shares	11.5
Corporate and Eliminations
Segment Information
Net sales	$ (266)	(199)
Income (loss) from continuing operations before income taxes	(156)	(1,173)
Income tax benefit (expense)	(16)	25
Income (loss) from continuing operations	(172)	(1,148)
Gain (loss) on derivative instrument		84
Mark to market gain (loss) on interest rate swaps	399	(669)
Anadarko acquisition-related costs	$ 41	$ 148