SEGMENT INFORMATION - Expenses (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Segment information
Stock-based compensation expense	$ 16.7	$ 19.5	$ 52.4	$ 53.0
Other operating expenses			22.4
Corporate and unallocated
Segment information
Payroll costs	63.4	61.7	189.7	173.5
Stock-based compensation expense	16.7	19.2	52.2	52.7
Professional service expenses	19.3	16.7	60.6	50.1
Intellectual property claim			$ 16.9
Other operating expenses	$ 14.8	$ 11.6		$ 35.5