Segment Information - Reconciliation of Income (Loss) before Income Taxes to Consolidated Adjusted EBITDAX Table (Detail) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2017		Dec. 31, 2016	Dec. 31, 2015
Segment Reporting [Abstract]
Income (loss) before income taxes		$ (1,688)		$ (3,829)	$ (9,689)
(Gains) losses on divestitures, net	[1]	(674)	[2]	757	1,022
Exploration expense		2,541		946	2,644
DD&A		4,279		4,301	4,603
Impairments		408		227	5,075
Interest expense		932		890	825
Total (gains) losses on derivatives, net, less net cash from settlement of commodity derivatives		156		559	235
Restructuring charges		21		389	0
Segment Reporting Information [Line Items]
Loss on early extinguishment of debt		2		155	0
Net income (loss) attributable to noncontrolling interests	[3]	245		263	(120)
Adjusted EBITDAX		5,732		4,075	4,936
Certain Other Nonoperating Items [Member]
Segment Reporting Information [Line Items]
Certain other nonoperating items		0		(58)	27
Deepwater Horizon [Member] | Judicial Ruling [Member]
Segment Reporting Information [Line Items]
Other operating expense		$ 0
Deepwater Horizon [Member] | Pending Litigation [Member]
Segment Reporting Information [Line Items]
Other operating expense				$ 1	$ 74

[1] Includes goodwill allocated to divestitures of $209 million in 2017, $397 million in 2016, and $184 million in 2015.

[2] Includes the $126 million gain related to the property exchange discussed above.

[3] Presentation has been adjusted to align with the current analysis of segment performance. Net income (loss) attributable to noncontrolling interests, previously reported within the Midstream segment, is now presented within Other and Intersegment Eliminations. Other revenues, previously reported within Other and Intersegment Eliminations, is now presented within the applicable segments.