Suspended Exploratory Well Costs - Rollforward (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015		Dec. 31, 2014		Dec. 31, 2013
Increase (Decrease) in Capitalized Exploratory Well Costs that are Pending Determination of Proved Reserves [Roll Forward]
Balance at January 1	$ 1,522		$ 2,232		$ 2,062
Additions pending the determination of proved reserves	461		421		848
Divestitures and other (1)	(33)		(913)	[1]	(48)
Reclassifications to proved properties	(104)		(100)		(507)
Charges to exploration expense (2)	(722)	[2]	(118)		(123)
Balance at December 31	1,124		1,522		$ 2,232
Offshore Area 1 in Mozambique [Member] | Oil and Gas Exploration and Production Reporting Segment [Member]
Increase (Decrease) in Capitalized Exploratory Well Costs that are Pending Determination of Proved Reserves [Roll Forward]
Divestitures and other (1)			$ (744)
Working interest sold			10.00%
Brazil Wells [Member] | Oil and Gas Exploration and Production Reporting Segment [Member]
Increase (Decrease) in Capitalized Exploratory Well Costs that are Pending Determination of Proved Reserves [Roll Forward]
Charges to exploration expense (2)	$ (565)

[1] Includes $(744) million during 2014 related to the Company’s sale of a 10% working interest in Offshore Area 1 in Mozambique.

[2] Includes $(565) million during 2015 related to Brazil. Given the current oil-price environment and other considerations, the Company does not expect to have substantive exploration and development activities in Brazil in the foreseeable future.