Segment Information - Selected Financial Information for Anadarko's Reporting Segments Table (Detail) - USD ($) $ in Millions		3 Months Ended			9 Months Ended
		Sep. 30, 2017		Sep. 30, 2016	Sep. 30, 2017		Sep. 30, 2016
Segment Reporting Information [Line Items]
Revenues		$ 2,610		$ 2,251	$ 7,927		$ 5,870
Other	[1]	80		56	237		128
Total revenues and other		2,496		1,893	8,979		5,482
Operating costs and expenses		3,271		2,686	9,989		7,471
Net cash from settlement of commodity derivatives					21		229
Other (income) expense, net		(21)		(31)	(43)		(86)
Net income (loss) attributable to noncontrolling interests		58	[1]	83	182	[1]	200
Total expenses and other		1,455		1,163	4,096		3,282
Consolidated Adjusted EBITDAX		1,235		1,144	4,066		2,724
(Gains) losses on derivatives, net [Member] | Commodity Contract [Member]
Segment Reporting Information [Line Items]
Net cash from settlement of commodity derivatives		(16)		(63)	(23)		(226)
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					(2)		8
Excluding Gains Losses On Divestitures Net [Member]
Segment Reporting Information [Line Items]
Total revenues and other	[2]	2,690		2,307	8,164		5,998
Excluding Certain Items [Member]
Segment Reporting Information [Line Items]
Operating costs and expenses	[3]	1,434		1,174	3,980		3,338
Excluding Certain Other Nonoperating Items [Member]
Segment Reporting Information [Line Items]
Other (income) expense, net		(21)		(31)	(43)		(30)
Exploration and Production [Member]
Segment Reporting Information [Line Items]
Revenues		2,101		1,901	6,510		4,975
Other	[1]	6		(2)	16		(17)
Exploration and Production [Member] | Intersegment Revenues [Member]
Segment Reporting Information [Line Items]
Revenues		0		0	0		0
Midstream [Member]
Segment Reporting Information [Line Items]
Revenues		496		329	1,346		823
Other	[1]	39		35	126		76
Midstream [Member] | Intersegment Revenues [Member]
Segment Reporting Information [Line Items]
Revenues		158		227	507		671
Operating Segments [Member]
Segment Reporting Information [Line Items]
Other (income) expense, net				0			0
Operating Segments [Member] | (Gains) losses on derivatives, net [Member] | Commodity Contract [Member]
Segment Reporting Information [Line Items]
Net cash from settlement of commodity derivatives		0		0	0		0
Operating Segments [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] | Excluding Certain Other Nonoperating Items [Member]
Segment Reporting Information [Line Items]
Other (income) expense, net		0			0
Operating Segments [Member] | Exploration and Production [Member]
Segment Reporting Information [Line Items]
Total expenses and other		959		877	2,687		2,586
Consolidated Adjusted EBITDAX		1,148		1,022	3,839		2,372
Operating Segments [Member] | Exploration and Production [Member] | Excluding Gains Losses On Divestitures Net [Member]
Segment Reporting Information [Line Items]
Total revenues and other	[2]	2,107		1,899	6,526		4,958
Operating Segments [Member] | Exploration and Production [Member] | Excluding Certain Items [Member]
Segment Reporting Information [Line Items]
Operating costs and expenses	[3]	959		877	2,687		2,586
Operating Segments [Member] | Midstream [Member]
Segment Reporting Information [Line Items]
Total expenses and other		391		284	1,063		714
Consolidated Adjusted EBITDAX		302		307	916		856
Operating Segments [Member] | Midstream [Member] | Excluding Gains Losses On Divestitures Net [Member]
Segment Reporting Information [Line Items]
Total revenues and other	[2]	693		591	1,979		1,570
Operating Segments [Member] | Midstream [Member] | Excluding Certain Items [Member]
Segment Reporting Information [Line Items]
Operating costs and expenses	[3]	391		284	1,063		714
Other and Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Revenues		13		21	71		72
Other	[1]	35		23	95		69
Net income (loss) attributable to noncontrolling interests		58	[1]	83	182	[1]	200
Total expenses and other		105		2	346		(18)
Consolidated Adjusted EBITDAX		(215)		(185)	(689)		(504)
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		(16)		(63)	(23)		(226)
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					(2)		8
Other and Intersegment Eliminations [Member] | Excluding Gains Losses On Divestitures Net [Member]
Segment Reporting Information [Line Items]
Total revenues and other	[2]	(110)		(183)	(341)		(530)
Other and Intersegment Eliminations [Member] | Excluding Certain Items [Member]
Segment Reporting Information [Line Items]
Operating costs and expenses	[3]	84		13	230		38
Other and Intersegment Eliminations [Member] | Excluding Certain Other Nonoperating Items [Member]
Segment Reporting Information [Line Items]
Other (income) expense, net		(21)		(31)	(43)		(30)
Other and Intersegment Eliminations [Member] | Intersegment Revenues [Member]
Segment Reporting Information [Line Items]
Revenues		$ (158)		$ (227)	$ (507)		$ (671)

[1] Presentation has been adjusted to align with the current analysis of segment performance. Net income (loss) attributable to noncontrolling interests, previously reported within the Midstream segment, is now presented within Other and Intersegment Eliminations. Other revenues, previously reported within Other and Intersegment Eliminations, is now presented within the applicable segments.

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

[3] 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.