Acquisitions and Divestitures - Summary of Carrying Amount of Major Assets and Liabilities Associated with Disposition (Detail) (USD $) In Millions, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
ASSETS
Current assets	$ 5,463	$ 6,366
Net property and equipment	52,752	52,421
LIABILITIES
Current debt		53
Other current liabilities	2,512	2,611
Asset retirement obligations	2,996	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