Income Taxes - Schedule of 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 Expense Benefit [Line Items]
Current, Federal	$ 604	$ (119)	$ 401
Current, State	58	(12)	26
Current, Foreign	43	44	33
Deferred, Federal	167	714	161
Deferred, State	(8)	71	17
Deferred, Foreign	24	21	20
Provision for income taxes	$ 888	$ 719	$ 658