Segment Information - Selected Financial Information for Anadarko's Reporting Segments Table (Detail) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Segment Reporting Information [Line Items]
Revenues		$ 2,637	$ 4,385	$ 5,222	$ 8,723
Gains (losses) on divestitures and other, net		(1)	54	(265)	1,560
Total revenues and other		2,636	4,439	4,957	10,283
Operating costs and expenses (1)	[1]	1,199	1,470	2,602	2,913
Net cash from settlement of commodity derivatives				(172)	186
Other (income) expense, net		15	(13)	62	(12)
Net income attributable to noncontrolling interests		47	39	79	82
Total expenses and other		1,179	1,584	2,549	3,163
Consolidated Adjusted EBITDAX		1,457	2,857	2,409	7,124
(Gains) Losses on Derivatives, Net [Member] | Commodity Contract [Member]
Segment Reporting Information [Line Items]
Net cash from settlement of commodity derivatives		(82)	88	(172)	180
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		0	2	1	4
Excluding Certain Other Nonoperating Items [Member]
Segment Reporting Information [Line Items]
Other (income) expense, net	[2]	15	(13)	40	(12)
Other and Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Revenues		0	0	0	0
Gains (losses) on divestitures and other, net		91	45	165	93
Total revenues and other		(143)	(165)	(297)	(301)
Operating costs and expenses (1)	[1]	(59)	7	(96)	25
Total expenses and other		(126)	82	(228)	193
Consolidated Adjusted EBITDAX		(17)	(247)	(69)	(494)
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		(82)	88	(172)	180
Other and Intersegment Eliminations [Member] | Excluding Certain Other Nonoperating Items [Member]
Segment Reporting Information [Line Items]
Other (income) expense, net	[2]	15	(13)	40	(12)
Other and Intersegment Eliminations [Member] | Intersegment Revenues [Member]
Segment Reporting Information [Line Items]
Revenues		(234)	(210)	(462)	(394)
Oil and Gas Exploration and Production Reporting Segment [Member]
Segment Reporting Information [Line Items]
Revenues		1,356	2,223	2,426	4,612
Gains (losses) on divestitures and other, net		(95)	10	(433)	1,470
Oil and Gas Exploration and Production Reporting Segment [Member] | Intersegment Revenues [Member]
Segment Reporting Information [Line Items]
Revenues		885	1,790	2,002	3,343
Oil and Gas Exploration and Production Reporting Segment [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Total revenues and other		2,146	4,023	3,995	9,425
Operating costs and expenses (1)	[1]	832	1,026	1,834	2,038
Total expenses and other		832	1,026	1,834	2,038
Consolidated Adjusted EBITDAX		1,314	2,997	2,161	7,387
Midstream Reporting Segment [Member]
Segment Reporting Information [Line Items]
Revenues		191	119	365	239
Gains (losses) on divestitures and other, net		3	(1)	3	(3)
Midstream Reporting Segment [Member] | Intersegment Revenues [Member]
Segment Reporting Information [Line Items]
Revenues		303	326	605	646
Midstream Reporting Segment [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Total revenues and other		497	444	973	882
Operating costs and expenses (1)	[1]	234	251	474	483
Net income attributable to noncontrolling interests		47	39	79	82
Total expenses and other		281	290	553	565
Consolidated Adjusted EBITDAX		216	154	420	317
Marketing Reporting Segment [Member]
Segment Reporting Information [Line Items]
Revenues		1,090	2,043	2,431	3,872
Gains (losses) on divestitures and other, net		0	0	0	0
Marketing Reporting Segment [Member] | Intersegment Revenues [Member]
Segment Reporting Information [Line Items]
Revenues		(954)	(1,906)	(2,145)	(3,595)
Marketing Reporting Segment [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Total revenues and other		136	137	286	277
Operating costs and expenses (1)	[1]	192	186	390	367
Total expenses and other		192	186	390	367
Consolidated Adjusted EBITDAX		(56)	(47)	(103)	(86)
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		$ 0	$ 2	$ 1	$ 4

[1] Operating costs and expenses excludes exploration expense, DD&A, impairments, and Deepwater Horizon settlement and related costs 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.