Segment Information - Selected Financial Information for Anadarko's Reporting Segments Table (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2013		Mar. 31, 2012
Segment Reporting Information [Line Items]
Sales revenues	$ 3,718		$ 3,412
Gains (losses) on divestitures and other, net	175		35
Total	3,893		3,447
Operating costs and expenses	1,253	[1]	1,317	[1]
Other (income) expense, net	(6)		265
Net income attributable to noncontrolling interests	24		27
Total expenses and other	1,220		1,197
Unrealized (gains) losses on derivatives, net included in marketing revenue	246		(142)
Adjusted EBITDAX	2,677		2,255
Excluding Tronox Related Contingent Loss [Member]
Segment Reporting Information [Line Items]
Other (income) expense, net	(6)	[2]	(10)	[2]
Gathering, Processing, and Marketing Sales [Member] | Commodity Contract [Member]
Segment Reporting Information [Line Items]
Realized (gains) losses on derivatives, net	4		(2)
Unrealized (gains) losses on derivatives, net included in marketing revenue	4		5
(Gains) Losses on Derivatives, net [Member] | Commodity Contract [Member]
Segment Reporting Information [Line Items]
Realized (gains) losses on derivatives, net	(51)		(137)
Unrealized (gains) losses on derivatives, net included in marketing revenue	334		89
Oil and Gas Exploration and Production Reporting Segment [Member]
Segment Reporting Information [Line Items]
Sales revenues	1,541		1,899
Intersegment revenues	1,862		1,174
Gains (losses) on divestitures and other, net	4		(17)
Total	3,407		3,056
Operating costs and expenses	881	[1]	926	[1]
Total expenses and other	881		926
Adjusted EBITDAX	2,526		2,130
Midstream Reporting Segment [Member]
Segment Reporting Information [Line Items]
Sales revenues	84		87
Intersegment revenues	253		249
Gains (losses) on divestitures and other, net			(1)
Total	337		335
Operating costs and expenses	188	[1]	189	[1]
Net income attributable to noncontrolling interests	24		27
Total expenses and other	212		216
Adjusted EBITDAX	125		119
Marketing Reporting Segment [Member]
Segment Reporting Information [Line Items]
Sales revenues	2,093		1,426
Intersegment revenues	(1,966)		(1,295)
Total	127		131
Operating costs and expenses	164	[1]	154	[1]
Total expenses and other	164		154
Adjusted EBITDAX	(33)		(18)
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	4		5
Other and Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Intersegment revenues	(149)		(128)
Gains (losses) on divestitures and other, net	171		53
Total	22		(75)
Operating costs and expenses	20	[1]	48	[1]
Total expenses and other	(37)		(99)
Adjusted EBITDAX	59		24
Other and Intersegment Eliminations [Member] | Excluding Tronox Related Contingent Loss [Member]
Segment Reporting Information [Line Items]
Other (income) expense, net	(6)	[2]	(10)	[2]
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	$ (51)		$ (137)

[1] Operating costs and expenses excludes 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.