SHARE-BASED COMPENSATION - Summary of Share-based Compensation Expense (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Components and classification of share-based compensation expense
Share-based compensation expense	$ 27	$ 26	$ 81	$ 77
Research and development expenses
Components and classification of share-based compensation expense
Share-based compensation expense	3	2	9	7
Selling, general and administrative expenses
Components and classification of share-based compensation expense
Share-based compensation expense	24	24	72	70
Stock options
Components and classification of share-based compensation expense
Share-based compensation expense	4	5	12	17
RSUs
Components and classification of share-based compensation expense
Share-based compensation expense	$ 23	$ 21	$ 69	$ 60