Leased Assets - Rental Expense (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Leases [Abstract]
Total rental expense	$ 167	$ 248	$ 355
Less: Income from subleases	10	17	15
Net rental expense	$ 157	$ 231	$ 340