Inventories (Detail) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Inventory Disclosure [Abstract]
Raw materials	$ 2,997	$ 2,789
Work in process and other	2,315	2,506
Finished manufactured goods	4,179	4,033
Goods acquired for resale	6,696	6,399
Total inventory	$ 16,187	$ 15,727