Inventories - (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Inventory, Net [Abstract]
Inventory valuation reserves	$ 360	$ 260
Finished goods	2,597	1,585
Work in process and raw materials	1,993	1,639
Total inventories, net	4,590	3,224
Inventory Impairment	$ 157	$ 138