Exit and Severance Costs - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Restructuring And Related Activities [Abstract]
Exit related costs	$ 21	$ 4	$ 27	$ 24
Employee Severance Expense		$ 28		$ 61
Payments for accrued severance costs	$ 9		$ 37