Segment Information - Selected Financial Information for Anadarko's Reporting Segments Table (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended				6 Months Ended
	Jun. 30, 2013		Jun. 30, 2012		Jun. 30, 2013		Jun. 30, 2012
Segment Reporting Information [Line Items]
Sales revenues	$ 3,440		$ 3,200		$ 7,158		$ 6,612
Gains (losses) on divestitures and other, net	57		22		232		57
Total	3,497		3,222		7,390		6,669
Operating costs and expenses (1)	1,225	[1]	1,238	[1]	2,478	[1]	2,555	[1]
Other (income) expense, net	98		(519)		92		(254)
Net income attributable to noncontrolling interests	30		19		54		46
Total expenses and other	1,247		1,000		2,467		2,197
Unrealized (gains) losses on derivatives, net included in marketing revenue					(395)		83
Adjusted EBITDAX	2,244		2,230		4,921		4,485
Gathering, Processing, and Marketing Sales [Member] | Commodity Contract [Member]
Segment Reporting Information [Line Items]
Realized (gains) losses on derivatives, net	3	[2]	(1)	[2]	7	[2]	(3)	[2]
Unrealized (gains) losses on derivatives, net included in marketing revenue	(6)	[2]	8	[2]	(2)	[2]	13	[2]
(Gains) Losses on Derivatives, net [Member] | Commodity Contract [Member]
Segment Reporting Information [Line Items]
Realized (gains) losses on derivatives, net	(21)		(263)		(72)		(400)
Unrealized (gains) losses on derivatives, net included in marketing revenue	(373)		(157)		(39)		(68)
Excluding Certain Other Nonoperating Items [Member]
Segment Reporting Information [Line Items]
Other (income) expense, net	13	[3]	6	[3]	7	[3]	(4)	[3]
Oil and Gas Exploration and Production Reporting Segment [Member]
Segment Reporting Information [Line Items]
Sales revenues	1,587		1,888		3,128		3,787
Intersegment revenues	1,526		1,035		3,388		2,209
Gains (losses) on divestitures and other, net	1		(12)		5		(29)
Total	3,114		2,911		6,521		5,967
Operating costs and expenses (1)	845	[1]	873	[1]	1,726	[1]	1,799	[1]
Total expenses and other	845		873		1,726		1,799
Adjusted EBITDAX	2,269		2,038		4,795		4,168
Midstream Reporting Segment [Member]
Segment Reporting Information [Line Items]
Sales revenues	88		81		172		168
Intersegment revenues	265		220		518		469
Gains (losses) on divestitures and other, net			(1)				(2)
Total	353		300		690		635
Operating costs and expenses (1)	209	[1]	174	[1]	397	[1]	363	[1]
Net income attributable to noncontrolling interests	30		19		54		46
Total expenses and other	239		193		451		409
Adjusted EBITDAX	114		107		239		226
Marketing Reporting Segment [Member]
Segment Reporting Information [Line Items]
Sales revenues	1,765		1,231		3,858		2,657
Intersegment revenues	(1,639)		(1,124)		(3,605)		(2,419)
Total	126		107		253		238
Operating costs and expenses (1)	164	[1]	158	[1]	328	[1]	312	[1]
Total expenses and other	164		158		328		312
Adjusted EBITDAX	(44)		(43)		(77)		(61)
Marketing Reporting Segment [Member] | Gathering, Processing, and Marketing Sales [Member] | Commodity Contract [Member]
Segment Reporting Information [Line Items]
Unrealized (gains) losses on derivatives, net included in marketing revenue	(6)		8		(2)		13
Other and Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Intersegment revenues	(152)		(131)		(301)		(259)
Gains (losses) on divestitures and other, net	56		35		227		88
Total	(96)		(96)		(74)		(171)
Operating costs and expenses (1)	7	[1]	33	[1]	27	[1]	81	[1]
Total expenses and other	(1)		(224)		(38)		(323)
Adjusted EBITDAX	(95)		128		(36)		152
Other and Intersegment Eliminations [Member] | (Gains) Losses on Derivatives, net [Member] | Commodity Contract [Member]
Segment Reporting Information [Line Items]
Realized (gains) losses on derivatives, net	(21)		(263)		(72)		(400)
Other and Intersegment Eliminations [Member] | Excluding Certain Other Nonoperating Items [Member]
Segment Reporting Information [Line Items]
Other (income) expense, net	$ 13	[3]	$ 6	[3]	$ 7	[3]	$ (4)	[3]

[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.