Income Taxes - Components of Total Deferred Taxes Table (Detail) (USD $) In Millions, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Deferred Tax Assets (Liabilities), Net [Line Items]
Total deferred taxes	$ (8,431)	$ (8,341)
Federal [Member]
Deferred Tax Assets (Liabilities), Net [Line Items]
Total deferred taxes	(7,890)	(7,916)
State, net of federal [Member]
Deferred Tax Assets (Liabilities), Net [Line Items]
Total deferred taxes	(325)	(252)
Foreign [Member]
Deferred Tax Assets (Liabilities), Net [Line Items]
Total deferred taxes	$ (216)	$ (173)