Segment Information - Selected Financial Information for Anadarko's Reporting Segments Table (Detail) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2018	Mar. 31, 2017
Segment Reporting Information [Line Items]
Revenues		$ 3,026	$ 2,898
Other		43	65
Total revenues and other		3,045	3,767
Operating costs and expenses		2,494	3,867
Net cash from settlement of commodity derivatives		63	8
Other (income) expense, net		(12)	2
Net income (loss) attributable to noncontrolling interests		53	43
Total expenses and other		1,426	1,347
Consolidated Adjusted EBITDAX		1,649	1,614
(Gains) losses on derivatives, net [Member] | Commodity Contract [Member]
Segment Reporting Information [Line Items]
Net cash from settlement of commodity derivatives		68	6
Gathering, processing, and marketing sales [Member] | Commodity Contract [Member] | Not Designated as Hedging Instrument [Member]
Segment Reporting Information [Line Items]
Total (gains) losses on derivatives, net included in marketing revenue, less net cash from settlement		6	(2)
Excluding Gains Losses On Divestitures Net [Member]
Segment Reporting Information [Line Items]
Total revenues and other	[1]	3,069	2,963
Excluding Certain Items [Member]
Segment Reporting Information [Line Items]
Operating costs and expenses	[2]	1,317	1,296
Excluding Certain Other Nonoperating Items [Member]
Segment Reporting Information [Line Items]
Other (income) expense, net		(12)	2
Operating Segments [Member] | Exploration and Production [Member]
Segment Reporting Information [Line Items]
Revenues		2,656	2,451
Other		(9)	2
Total revenues and other		2,624
Net income (loss) attributable to noncontrolling interests		0	0
Total expenses and other		876	923
Consolidated Adjusted EBITDAX		1,781	1,533
Operating Segments [Member] | Exploration and Production [Member] | (Gains) losses on derivatives, net [Member] | Commodity Contract [Member]
Segment Reporting Information [Line Items]
Net cash from settlement of commodity derivatives		0	0
Operating Segments [Member] | Exploration and Production [Member] | Gathering, processing, and marketing sales [Member] | Commodity Contract [Member] | Not Designated as Hedging Instrument [Member]
Segment Reporting Information [Line Items]
Total (gains) losses on derivatives, net included in marketing revenue, less net cash from settlement		0	0
Operating Segments [Member] | Exploration and Production [Member] | Excluding Gains Losses On Divestitures Net [Member]
Segment Reporting Information [Line Items]
Total revenues and other	[1]	2,657	2,456
Operating Segments [Member] | Exploration and Production [Member] | Excluding Certain Items [Member]
Segment Reporting Information [Line Items]
Operating costs and expenses	[2]	876	923
Operating Segments [Member] | Exploration and Production [Member] | Excluding Certain Other Nonoperating Items [Member]
Segment Reporting Information [Line Items]
Other (income) expense, net		0	0
Operating Segments [Member] | Exploration and Production [Member] | Intersegment Revenues [Member]
Segment Reporting Information [Line Items]
Revenues		10	3
Operating Segments [Member] | WES Midstream [Member]
Segment Reporting Information [Line Items]
Revenues		310	366
Other		29	30
Total revenues and other		466
Net income (loss) attributable to noncontrolling interests		0	0
Total expenses and other		194	292
Consolidated Adjusted EBITDAX		272	255
Operating Segments [Member] | WES Midstream [Member] | (Gains) losses on derivatives, net [Member] | Commodity Contract [Member]
Segment Reporting Information [Line Items]
Net cash from settlement of commodity derivatives		0	0
Operating Segments [Member] | WES Midstream [Member] | Gathering, processing, and marketing sales [Member] | Commodity Contract [Member] | Not Designated as Hedging Instrument [Member]
Segment Reporting Information [Line Items]
Total (gains) losses on derivatives, net included in marketing revenue, less net cash from settlement		0	0
Operating Segments [Member] | WES Midstream [Member] | Excluding Gains Losses On Divestitures Net [Member]
Segment Reporting Information [Line Items]
Total revenues and other	[1]	466	547
Operating Segments [Member] | WES Midstream [Member] | Excluding Certain Items [Member]
Segment Reporting Information [Line Items]
Operating costs and expenses	[2]	194	292
Operating Segments [Member] | WES Midstream [Member] | Excluding Certain Other Nonoperating Items [Member]
Segment Reporting Information [Line Items]
Other (income) expense, net		0	0
Operating Segments [Member] | WES Midstream [Member] | Intersegment Revenues [Member]
Segment Reporting Information [Line Items]
Revenues		127	151
Operating Segments [Member] | Other Midstream [Member]
Segment Reporting Information [Line Items]
Revenues		36	36
Other		10	6
Total revenues and other		107
Net income (loss) attributable to noncontrolling interests		0	0
Total expenses and other		54	50
Consolidated Adjusted EBITDAX		44	34
Operating Segments [Member] | Other Midstream [Member] | (Gains) losses on derivatives, net [Member] | Commodity Contract [Member]
Segment Reporting Information [Line Items]
Net cash from settlement of commodity derivatives		0	0
Operating Segments [Member] | Other Midstream [Member] | Gathering, processing, and marketing sales [Member] | Commodity Contract [Member] | Not Designated as Hedging Instrument [Member]
Segment Reporting Information [Line Items]
Total (gains) losses on derivatives, net included in marketing revenue, less net cash from settlement		0	0
Operating Segments [Member] | Other Midstream [Member] | Excluding Gains Losses On Divestitures Net [Member]
Segment Reporting Information [Line Items]
Total revenues and other	[1]	98	84
Operating Segments [Member] | Other Midstream [Member] | Excluding Certain Items [Member]
Segment Reporting Information [Line Items]
Operating costs and expenses	[2]	54	50
Operating Segments [Member] | Other Midstream [Member] | Excluding Certain Other Nonoperating Items [Member]
Segment Reporting Information [Line Items]
Other (income) expense, net		0	0
Operating Segments [Member] | Other Midstream [Member] | Intersegment Revenues [Member]
Segment Reporting Information [Line Items]
Revenues		52	42
Other and Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Revenues		24	45
Other		13	27
Total revenues and other		(152)
Net income (loss) attributable to noncontrolling interests		53	43
Total expenses and other		302	82
Consolidated Adjusted EBITDAX		(448)	(208)
Other and Intersegment Eliminations [Member] | (Gains) losses on derivatives, net [Member] | Commodity Contract [Member]
Segment Reporting Information [Line Items]
Net cash from settlement of commodity derivatives		68	6
Other and Intersegment Eliminations [Member] | Gathering, processing, and marketing sales [Member] | Commodity Contract [Member] | Not Designated as Hedging Instrument [Member]
Segment Reporting Information [Line Items]
Total (gains) losses on derivatives, net included in marketing revenue, less net cash from settlement		6	(2)
Other and Intersegment Eliminations [Member] | Excluding Gains Losses On Divestitures Net [Member]
Segment Reporting Information [Line Items]
Total revenues and other	[1]	(152)	(124)
Other and Intersegment Eliminations [Member] | Excluding Certain Items [Member]
Segment Reporting Information [Line Items]
Operating costs and expenses	[2]	193	31
Other and Intersegment Eliminations [Member] | Excluding Certain Other Nonoperating Items [Member]
Segment Reporting Information [Line Items]
Other (income) expense, net		(12)	2
Other and Intersegment Eliminations [Member] | Intersegment Revenues [Member]
Segment Reporting Information [Line Items]
Revenues		$ (189)	$ (196)

[1] Total revenues and other excludes gains (losses) on divestitures, net since these gains and losses are excluded from Adjusted EBITDAX.

[2] Operating costs and expenses excludes exploration expense, DD&A, impairments, restructuring charges, and certain other operating expenses since these expenses are excluded from Adjusted EBITDAX.