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Inventories - Additional information (Details) - USD ($)
$ in Millions
 12 Months Ended
Dec. 31, 2019
Dec. 31, 2018
Dec. 31, 2017
Disclosure Of Inventories [Line Items]      
Inventory write-down $ 140 $ 148 $ 73
Reversal of inventory write-down 65 56 15
Cost of net sales [member]      
Disclosure Of Inventories [Line Items]      
Cost of inventories recognised as expense during period 2,200 2,200 2,100
Cost of other revenue [member]      
Disclosure Of Inventories [Line Items]      
Cost of inventories recognised as expense during period $ 127 $ 0 $ 0