Properties and Equipment (Detail) - USD ($) $ in Millions		Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Property, Plant, and Equipment [Line Items]
Gross properties and equipment		$ 70,683	$ 75,107
Less accumulated depreciation, depletion, and amortization		36,932	33,518
Net properties and equipment		33,751	41,589	$ 40,929
Oil and Gas Exploration and Production Reporting Segment [Member]
Property, Plant, and Equipment [Line Items]
Gross properties and equipment	[1]	59,389	63,674
Costs associated with unproved properties		3,500	5,100
Midstream Reporting Segment [Member]
Property, Plant, and Equipment [Line Items]
Gross properties and equipment		8,458	8,647
Other [Member]
Property, Plant, and Equipment [Line Items]
Gross properties and equipment		$ 2,836	$ 2,786

[1] Includes costs associated with unproved properties of $3.5 billion at December 31, 2015, and $5.1 billion at December 31, 2014.