Exit and Disposal Costs - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	9 Months Ended			3 Months Ended	9 Months Ended
	Sep. 30, 2013	Sep. 30, 2013 Continuing operations [Member] Exploration and Production [Member]	Sep. 30, 2013 Continuing operations [Member] Corporate and Other [Member]	Dec. 31, 2013 Continuing operations [Member] Scenario, Forecast [Member] Facility and Other Exit Costs [Member] Leased Office Space [Member]	Sep. 30, 2013 Discontinued operations-Downstream businesses [Member]	Sep. 30, 2013 Discontinued operations-Downstream businesses [Member] Scenario, Forecast [Member] Facility and Other Exit Costs [Member] Port Reading Refinery [Member]
Restructuring Cost and Reserve [Line Items]
Enhanced benefit arrangements	$ 80	$ 10	$ 25		$ 45
Expected additional facility exit costs						25
Office closure costs				$ 35