Segment Information - Selected Financial Information for Anadarko's Reporting Segments Table (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended				9 Months Ended
	Sep. 30, 2014		Sep. 30, 2013		Sep. 30, 2014		Sep. 30, 2013
Segment Reporting Information [Line Items]
Revenues	$ 4,230		$ 3,789		$ 12,953		$ 10,947
Gains (losses) on divestitures and other, net	780		64		2,340		296
Total revenues and other	5,010		3,853		15,293		11,243
Operating costs and expenses (1)	1,553	[1]	1,298	[1]	4,466	[1]	3,776	[1]
Net cash from settlement of commodity derivatives					138		(37)
Other (income) expense, net	24		(23)		12		69
Net income attributable to noncontrolling interests	60		41		142		95
Total expenses and other	1,567		1,352		4,730		3,819
Adjusted EBITDAX	3,442		2,491		10,566		7,412
(Gains) Losses on Derivatives, net [Member] | Commodity Contract [Member]
Segment Reporting Information [Line Items]
Net cash from settlement of commodity derivatives	(48)		26		132		(46)
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	(1)		(10)		3		(12)
Excluding Certain Other Nonoperating Items [Member]
Segment Reporting Information [Line Items]
Other (income) expense, net	2	[2]	(13)	[2]	(10)	[2]	(6)	[2]
Other and Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Revenues	0		0		0		0
Gains (losses) on divestitures and other, net	55		57		148		284
Total revenues and other	(139)		(117)		(440)		(191)
Operating costs and expenses (1)	26	[1]	(12)	[1]	51	[1]	15	[1]
Total expenses and other	(20)		1		173		(37)
Adjusted EBITDAX	(119)		(118)		(613)		(154)
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	(48)		26		132		(46)
Other and Intersegment Eliminations [Member] | Excluding Certain Other Nonoperating Items [Member]
Segment Reporting Information [Line Items]
Other (income) expense, net	2	[2]	(13)	[2]	(10)	[2]	(6)	[2]
Other and Intersegment Eliminations [Member] | Intersegment Revenues [Member]
Segment Reporting Information [Line Items]
Revenues	(194)		(174)		(588)		(475)
Oil and Gas Exploration and Production Reporting Segment [Member]
Segment Reporting Information [Line Items]
Revenues	2,192		1,916		6,804		5,044
Gains (losses) on divestitures and other, net	724		7		2,194		12
Oil and Gas Exploration and Production Reporting Segment [Member] | Intersegment Revenues [Member]
Segment Reporting Information [Line Items]
Revenues	1,604		1,516		4,947		4,904
Oil and Gas Exploration and Production Reporting Segment [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Total revenues and other	4,520		3,439		13,945		9,960
Operating costs and expenses (1)	1,090	[1]	930	[1]	3,128	[1]	2,656	[1]
Total expenses and other	1,090		930		3,128		2,656
Adjusted EBITDAX	3,430		2,509		10,817		7,304
Midstream Reporting Segment [Member]
Segment Reporting Information [Line Items]
Revenues	119		95		358		267
Gains (losses) on divestitures and other, net	1		0		(2)		0
Midstream Reporting Segment [Member] | Intersegment Revenues [Member]
Segment Reporting Information [Line Items]
Revenues	364		287		1,010		805
Midstream Reporting Segment [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Total revenues and other	484		382		1,366		1,072
Operating costs and expenses (1)	249	[1]	216	[1]	732	[1]	613	[1]
Net income attributable to noncontrolling interests	60		41		142		95
Total expenses and other	309		257		874		708
Adjusted EBITDAX	175		125		492		364
Marketing Reporting Segment [Member]
Segment Reporting Information [Line Items]
Revenues	1,919		1,778		5,791		5,636
Gains (losses) on divestitures and other, net	0		0		0		0
Marketing Reporting Segment [Member] | Intersegment Revenues [Member]
Segment Reporting Information [Line Items]
Revenues	(1,774)		(1,629)		(5,369)		(5,234)
Marketing Reporting Segment [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Total revenues and other	145		149		422		402
Operating costs and expenses (1)	188	[1]	164	[1]	555	[1]	492	[1]
Total expenses and other	188		164		555		492
Adjusted EBITDAX	(44)		(25)		(130)		(102)
Marketing Reporting Segment [Member] | 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	$ (1)		$ (10)		$ 3		$ (12)

[1] Operating costs and expenses excludes exploration expense, DD&A, impairments, Deepwater Horizon settlement and related costs, and Algeria exceptional profits tax settlement since these expenses are excluded from Adjusted EBITDAX.

[2] Other (income) expense, net excludes certain other nonoperating items since these items are excluded from Adjusted EBITDAX.