Segments - Schedule of Industry Segments and Eliminations (Details) shares in Millions, $ in Millions	1 Months Ended	3 Months Ended		6 Months Ended
	Mar. 31, 2021 USD ($) shares	Jun. 30, 2021 USD ($)	Jun. 30, 2020 USD ($)	Jun. 30, 2021 USD ($) segment shares	Jun. 30, 2020 USD ($)
Segment Information
Number of operating segments | segment				3
Net sales		$ 5,958	$ 2,928	$ 11,251	$ 9,541
Income (loss) from continuing operations before income taxes		143	(8,184)	458	(10,222)
Income tax benefit (expense)		(43)	1,468	(59)	1,493
Income (loss) from continuing operations		100	(6,716)	399	(8,729)
Gain (loss) on derivative instrument		(223)	(76)	176	(661)
Anadarko acquisition-related costs		52	149	93	297
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		4,505	2,040	8,169	7,100
Income (loss) from continuing operations before income taxes		631	(7,734)	569	(7,498)
Income tax benefit (expense)		0	0	0	0
Income (loss) from continuing operations		631	(7,734)	569	(7,498)
Impairment charge		21	6,400	156	7,000
Gain (loss) on derivative instrument		(140)		(180)	923
Operating Segments | Chemical
Segment Information
Net sales		1,187	846	2,275	1,808
Income (loss) from continuing operations before income taxes		312	108	563	294
Income tax benefit (expense)		0	0	0	0
Income (loss) from continuing operations		312	108	563	294
Operating Segments | Midstream and marketing
Segment Information
Net sales		497	204	1,304	994
Income (loss) from continuing operations before income taxes		(30)	(7)	252	(1,294)
Income tax benefit (expense)		0	0	0	0
Income (loss) from continuing operations		(30)	(7)	252	(1,294)
Gain (loss) on derivative instrument		(180)		(165)	305
Goodwill impairment					1,400
Operating Segments | Midstream and marketing | Disposed of by Sale, Not Discontinued Operations | WES Midstream segment
Segment Information
Gain on sale		22		$ 124
Number of limited partner units sold (in units) | shares				11.5
Corporate and Eliminations
Segment Information
Net sales		(231)	(162)	$ (497)	(361)
Income (loss) from continuing operations before income taxes		(770)	(551)	(926)	(1,724)
Income tax benefit (expense)		(43)	1,468	(59)	1,493
Income (loss) from continuing operations		(813)	917	(985)	(231)
Gain (loss) on derivative instrument			114		114
Mark to market gain (loss) on interest rate swaps		(223)		176	(665)
Anadarko acquisition-related costs		$ 52	149	$ 93	297
Gain (loss) related to warrants			$ (79)		$ 5