Property, Plant and Equipment - Net Changes in Capitalized Exploratory Well Costs (Detail) $ in Millions	12 Months Ended
	Dec. 31, 2016 USD ($) Well	Dec. 31, 2015 USD ($) Well	Dec. 31, 2014 USD ($) Well
Capitalized Exploratory Well Costs [Abstract]
Beginning balance	$ 1,415	$ 1,416	$ 2,045
Additions to capitalized exploratory well costs pending the determination of proved reserves	79	424	292
Reclassifications to wells, facilities and equipment based on the determination of proved reserves	0	(72)	(629)
Capitalized exploratory well costs charged to expense	(897)	(356)	(235)
Dispositions and other	0	3	(57)
Ending balance	$ 597	$ 1,415	$ 1,416
Number of Wells at December 31 | Well	17	35	37