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, 2013		Sep. 30, 2012		Sep. 30, 2013		Sep. 30, 2012
Segment Reporting Information [Line Items]
Revenue	$ 3,789		$ 3,283		$ 10,947		$ 9,895
Gains (losses) on divestitures and other, net	64		49		296		106
Total	3,853		3,332		11,243		10,001
Operating costs and expenses (1)	1,298	[1]	1,225	[1]	3,776	[1]	3,780	[1]
Other (income) expense, net	(23)		(10)		69		(264)
Net income attributable to noncontrolling interests	41		21		95		67
Total expenses and other	1,352		1,036		3,819		3,233
Unrealized (gains) losses on derivatives, net included in marketing revenue					(359)		539
Adjusted EBITDAX	2,491		2,301		7,412		6,786
Other and Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Revenue	(174)		(137)		(475)		(396)
Gains (losses) on divestitures and other, net	57		43		284		131
Total	(117)		(94)		(191)		(265)
Operating costs and expenses (1)	(12)	[1]	51	[1]	15	[1]	132	[1]
Total expenses and other	1		(159)		(37)		(482)
Adjusted EBITDAX	(118)		65		(154)		217
Gathering, Processing, and Marketing Sales [Member] | Commodity Contract [Member]
Segment Reporting Information [Line Items]
Realized (gains) losses on derivatives, net	2	[2]	3	[2]	9	[2]	0	[2]
Unrealized (gains) losses on derivatives, net included in marketing revenue	(10)	[2]	5	[2]	(12)	[2]	18	[2]
(Gains) Losses on Derivatives, net [Member] | Commodity Contract [Member]
Segment Reporting Information [Line Items]
Realized (gains) losses on derivatives, net	26		(200)		(46)		(600)
Unrealized (gains) losses on derivatives, net included in marketing revenue	120		437		81		369
(Gains) Losses on Derivatives, net [Member] | Commodity Contract [Member] | Other and Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Realized (gains) losses on derivatives, net	26		(200)		(46)		(600)
Excluding Certain Other Nonoperating Items [Member]
Segment Reporting Information [Line Items]
Other (income) expense, net	(13)	[3]	(10)	[3]	(6)	[3]	(14)	[3]
Excluding Certain Other Nonoperating Items [Member] | Other and Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Other (income) expense, net	(13)	[3]	(10)	[3]	(6)	[3]	(14)	[3]
Oil and Gas Exploration and Production Reporting Segment [Member]
Segment Reporting Information [Line Items]
Revenue	1,916		1,393		5,044		5,180
Gains (losses) on divestitures and other, net	7		12		12		(17)
Oil and Gas Exploration and Production Reporting Segment [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Total	3,439		2,992		9,960		8,959
Operating costs and expenses (1)	930	[1]	840	[1]	2,656	[1]	2,639	[1]
Total expenses and other	930		840		2,656		2,639
Adjusted EBITDAX	2,509		2,152		7,304		6,320
Oil and Gas Exploration and Production Reporting Segment [Member] | Intersegment Revenues [Member]
Segment Reporting Information [Line Items]
Revenue	1,516		1,587		4,904		3,796
Midstream Reporting Segment [Member]
Segment Reporting Information [Line Items]
Revenue	95		80		267		248
Gains (losses) on divestitures and other, net	0		(6)		0		(8)
Midstream Reporting Segment [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Total	382		306		1,072		941
Operating costs and expenses (1)	216	[1]	182	[1]	613	[1]	545	[1]
Net income attributable to noncontrolling interests	41		21		95		67
Total expenses and other	257		203		708		612
Adjusted EBITDAX	125		103		364		329
Midstream Reporting Segment [Member] | Intersegment Revenues [Member]
Segment Reporting Information [Line Items]
Revenue	287		232		805		701
Marketing Reporting Segment [Member]
Segment Reporting Information [Line Items]
Revenue	1,778		1,810		5,636		4,467
Gains (losses) on divestitures and other, net	0		0		0		0
Marketing Reporting Segment [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Total	149		128		402		366
Operating costs and expenses (1)	164	[1]	152	[1]	492	[1]	464	[1]
Total expenses and other	164		152		492		464
Adjusted EBITDAX	(25)		(19)		(102)		(80)
Marketing Reporting Segment [Member] | Intersegment Revenues [Member]
Segment Reporting Information [Line Items]
Revenue	(1,629)		(1,682)		(5,234)		(4,101)
Marketing Reporting Segment [Member] | Gathering, Processing, and Marketing Sales [Member] | Commodity Contract [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Unrealized (gains) losses on derivatives, net included in marketing revenue	$ (10)		$ 5		$ (12)		$ 18

[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] Represents the effect of marketing and trading derivative activities.

[3] Other (income) expense, net excludes Tronox-related contingent loss and certain other nonoperating items since these expenses are excluded from Adjusted EBITDAX.