Suspended Exploratory Well Costs (Detail) - USD ($)	6 Months Ended
	Jun. 30, 2015	Dec. 31, 2014
Capitalized Exploratory Well Costs [Abstract]
Suspended exploratory well costs	$ 1,700,000,000	$ 1,500,000,000
Exploratory well costs previously capitalized as suspended exploratory well costs for greater than one year at December 31, 2014, charged to dry hole expense	$ 0