INCOME TAXES - Schedule of (Benefit from) Provision for Income Taxes (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Federal
Current									$ 0.0	$ 0.0	$ 0.0
Deferred									23.3	31.2	33.4
Total federal tax expense (benefit)									23.3	31.2	33.4
State
Current									1.5	0.3	0.0
Deferred									0.4	(4.6)	10.6
Total state tax expense (benefit)									1.9	(4.3)	10.6
Foreign
Current									14.9	14.4	18.4
Deferred									3.5	0.1	(4.4)
Total foreign tax expense (benefit)									18.4	14.5	14.0
Provision for income taxes	$ 53.9	$ (12.8)	$ (3.2)	$ 5.7	$ 6.3	$ 10.2	$ 20.9	$ 4.0	$ 43.6	$ 41.4	$ 58.0