Income Taxes - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Income Tax Disclosure [Abstract]
Total unrecognized tax benefits	$ 180		$ 180
Tax benefits affecting effective tax rate	61		61
Unrecognized tax benefit impact in the next twelve months	14		14
Payment of interest accrued	12		12
Accrued penalties related to unrecognized tax benefits	1		1
Tax benefit of discontinued operations	$ 0	$ 2	$ 70	$ 1