Suspended Exploratory Well Costs (Detail) - USD ($) $ in Millions	9 Months Ended
Sep. 30, 2015	Dec. 31, 2014
Capitalized Exploratory Well Costs [Abstract]
Suspended exploratory well costs	$ 1,100	$ 1,500
Suspended exploratory well costs previously capitalized for greater than one year at December 31, 2014, charged to dry hole expense	$ 602

The amount of capitalized exploratory well costs that is pending the determination of proved reserves. This does not include amounts that were capitalized and subsequently expensed in the same annual period.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 932

-SubTopic 235

-Section 50

-Paragraph 1B

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=51678428&loc=SL6806780-109447

Name:	us-gaap_CapitalizedExploratoryWellCosts
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant