Contingencies - Subsequent Events (Detail) (Subsequent Event [Member], USD $)	0 Months Ended
Jan. 23, 2015	Jan. 15, 2015 bbl
Tronox Litigation [Member] \| Judicial Ruling [Member]
Subsequent Event [Line Items]
Payment for Tronox settlement	$ 5,200,000,000
Deepwater Horizon [Member] \| Pending Litigation [Member] \| Clean Water Act [Member]
Subsequent Event [Line Items]
Barrels of oil discharged		3,190,000

The amount of cash paid for the settlement of litigation or for other legal issues during the period.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 25

-Subparagraph (g)

-URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3536-108585

Name:	us-gaap_PaymentsForLegalSettlements
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration