Discontinued Operations - Summary of Sales and Other Operating Revenues and Income from Discontinued Operations (Detail) (Discontinued Downstream Businesses [Member], USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Discontinued Downstream Businesses [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Sales and other operating revenues	$ 12,273	$ 14,386	$ 17,132
Income from discontinued operations before income taxes	1,943	312	222
Current tax provision (benefit)
Deferred tax provision (benefit)	689	116	77
Provision for income taxes	689	116	77
Income from discontinued operations, net of income taxes	$ 1,254	$ 196	$ 145