Inventories - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2013	Dec. 31, 2014
Inventory Disclosure [Abstract]
Inventories valued on a LIFO basis	$ 1,373		$ 1,514
Total inventories valued on an average-cost basis	559		$ 767
Recognition of income caused by partial liquidations of the lower cost LIFO inventory base, gross	1	$ 26
Recognition of income caused by partial liquidations of the lower cost LIFO inventory base, after tax	$ 1	$ 17