Inventories - Narrative (Details) - USD ($) $ in Millions	3 Months Ended		12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2019	Dec. 31, 2018
Schedule of Inventory [Line Items]
Inventory write-downs			$ 649	$ 572
Inventory write-downs for excess raw materials
Schedule of Inventory [Line Items]
Inventory write-downs	$ 500	$ 410	$ 547	$ 440