Acquisitions and Divestitures - Summary of Carrying Amount of Major Assets and Liabilities Associated with Disposition (Detail) (USD $) In Millions, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013	Sep. 30, 2013
ASSETS
Current assets	$ 4,426	$ 6,366
Total assets	60,990	61,637	58,641
LIABILITIES
Current debt	20	53
Other current liabilities	2,794	2,611
Asset retirement obligations	3,096	3,101
Argentina Divestiture [Member]
ASSETS
Current assets		150
Net property and equipment		1,416
Other assets		12
Total assets		1,578
LIABILITIES
Current debt		51
Other current liabilities		95
Asset retirement obligations		91
Other long-term liabilities		21
Total liabilities		$ 258