SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Schedule of Stock-Based Compensation Expense (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Allocation of stock-based compensation expense
Total stock-based compensation expense	$ 81.3	$ 71.0	$ 61.6
Cost of sales
Allocation of stock-based compensation expense
Total stock-based compensation expense	14.7	11.4	9.2
Selling, general, and administrative expenses
Allocation of stock-based compensation expense
Total stock-based compensation expense	51.2	46.3	40.7
Research and development expenses
Allocation of stock-based compensation expense
Total stock-based compensation expense	$ 15.4	$ 13.3	$ 11.7