Provision for Income Taxes (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Income Tax [Line Items]
Federal	$ 708	$ 732	$ 786
States and Puerto Rico	61	62	63
Total current provision	769	794	849
Deferred (benefit) provision	(80)	22	(199)
Provision for income taxes	$ 689	$ 816	$ 650