Segment Information - Schedule of Identifiable Assets by Operating Segment (Detail) (USD $) In Millions, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013
Segment Reporting Information [Line Items]
Identifiable assets	$ 40,975	$ 42,754
Continuing Operations [Member]
Segment Reporting Information [Line Items]
Identifiable assets	40,603	40,007
Continuing Operations [Member] | Exploration and Production [Member]
Segment Reporting Information [Line Items]
Identifiable assets	36,895	37,863
Continuing Operations [Member] | Corporate, Interest and Other [Member]
Segment Reporting Information [Line Items]
Identifiable assets	3,708	2,144
Discontinued Operations [Member]
Segment Reporting Information [Line Items]
Identifiable assets	$ 372	$ 2,747