Segment Information - Selected Financial Information for Anadarko's Reporting Segments Table (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012		Dec. 31, 2011		Dec. 31, 2010
Segment Reporting Information [Line Items]
Sales revenues	$ 13,307		$ 13,882		$ 10,842
Gains (losses) on divestitures and other, net	104		85		142
Total	13,411		13,967		10,984
Operating costs and expenses	5,164	[1]	5,227	[1]	4,296	[1]
Other (income) expense, net	(254)		254		(119)
Net income attributable to noncontrolling interests	54		81		60
Total expenses and other	4,461		5,086		3,834
Unrealized (gains) losses on derivatives, net included in marketing revenue	377		616		(114)
Adjusted EBITDAX	8,966		8,869		7,146
Net properties and equipment	38,398		37,501		37,957
Capital expenditures	7,311		6,553		5,169
Goodwill	5,492		5,641		5,282
Excluding Tronox Related Contingent Loss [Member]
Segment Reporting Information [Line Items]
Other (income) expense, net	(4)	[2]	4	[2]	(24)	[2]
Gathering, Processing, and Marketing Sales [Member] | Commodity Derivatives [Member]
Segment Reporting Information [Line Items]
Realized (gains) losses on derivatives, net	2	[3]	20	[3]	3	[3]
Unrealized (gains) losses on derivatives, net included in marketing revenue	16	[3]	(12)	[3]	(4)	[3]
(Gains) Losses on Derivatives, net [Member] | Commodity Derivatives [Member]
Segment Reporting Information [Line Items]
Realized (gains) losses on derivatives, net	(753)		(226)		(498)
Unrealized (gains) losses on derivatives, net included in marketing revenue	366		(336)		(395)
Oil and Gas Exploration and Production Reporting Segment [Member]
Segment Reporting Information [Line Items]
Sales revenues	6,752		7,519		5,613
Intersegment revenues	5,318		5,005		4,136
Gains (losses) on divestitures and other, net	(65)		(41)
Total	12,005		12,483		9,749
Operating costs and expenses	3,505	[1]	3,696	[1]	2,963	[1]
Total expenses and other	3,505		3,696		2,963
Adjusted EBITDAX	8,500		8,787		6,786
Net properties and equipment	31,939		32,235		32,850
Capital expenditures	5,836		5,026		4,672
Goodwill	5,317		5,475		5,143
Midstream Reporting Segment [Member]
Segment Reporting Information [Line Items]
Sales revenues	325		342		192
Intersegment revenues	959		957		831
Gains (losses) on divestitures and other, net	(8)		(13)
Total	1,276		1,286		1,023
Operating costs and expenses	748	[1]	786	[1]	655	[1]
Net income attributable to noncontrolling interests	54		81		60
Total expenses and other	802		867		715
Adjusted EBITDAX	474		419		308
Net properties and equipment	4,459		3,432		3,303
Capital expenditures	1,250		1,420		384
Goodwill	175		166		139
Marketing Reporting Segment [Member]
Segment Reporting Information [Line Items]
Sales revenues	6,230		6,023		5,037
Intersegment revenues	(5,734)		(5,515)		(4,572)
Total	496		508		465
Operating costs and expenses	616	[1]	559	[1]	457	[1]
Total expenses and other	616		559		457
Adjusted EBITDAX	(104)		(63)		4
Net properties and equipment	94		9		9
Capital expenditures	70
Marketing Reporting Segment [Member] | Gathering, Processing, and Marketing Sales [Member] | Commodity Derivatives [Member]
Segment Reporting Information [Line Items]
Unrealized (gains) losses on derivatives, net included in marketing revenue	16		(12)		(4)
Other and Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Sales revenues			(2)
Intersegment revenues	(543)		(447)		(395)
Gains (losses) on divestitures and other, net	177		139		142
Total	(366)		(310)		(253)
Operating costs and expenses	295	[1]	186	[1]	221	[1]
Total expenses and other	(462)		(36)		(301)
Adjusted EBITDAX	96		(274)		48
Net properties and equipment	1,906		1,825		1,795
Capital expenditures	155		107		113
Other and Intersegment Eliminations [Member] | Excluding Tronox Related Contingent Loss [Member]
Segment Reporting Information [Line Items]
Other (income) expense, net	(4)	[2]	4	[2]	(24)	[2]
Other and Intersegment Eliminations [Member] | (Gains) Losses on Derivatives, net [Member] | Commodity Derivatives [Member]
Segment Reporting Information [Line Items]
Realized (gains) losses on derivatives, net	$ (753)		$ (226)		$ (498)

[1] Operating costs and expenses exclude exploration expense; depreciation, depletion, and amortization; 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 Tronox-related contingent loss since this expense is excluded from Adjusted EBITDAX.

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