ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS), NET (Details) - USD ($) $ in Millions	3 Months Ended						9 Months Ended
	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2020
AOCI Rollforward
Beginning balance	$ 3,286.3	$ 3,310.1	$ 3,355.6	$ 3,327.0	$ 3,285.4	$ 3,241.0	$ 3,355.6
Other comprehensive (loss) income	31.6	(2.7)	(37.5)	(17.2)	(18.1)	14.7
Ending balance	3,344.5	3,286.3	3,310.1	3,328.7	3,327.0	3,285.4	3,344.5
Accumulated Other Comprehensive Income (loss), net
AOCI Rollforward
Beginning balance	(2.6)	0.1	37.6	8.1	26.2	11.5	37.6
Other comprehensive (loss) income	31.6	(2.7)	(37.5)	(17.2)	(18.1)	14.7	(8.6)
Ending balance	29.0	$ (2.6)	0.1	$ (9.1)	$ 8.1	$ 26.2	29.0
Foreign Currency Translation
AOCI Rollforward
Beginning balance			38.2				38.2
Other comprehensive (loss) income							(9.4)
Ending balance	28.8						28.8
Unrealized Investment Gain/Loss
AOCI Rollforward
Beginning balance			0.2				0.2
Other comprehensive (loss) income							(0.3)
Ending balance	(0.1)						(0.1)
Post-Retirement Benefits
AOCI Rollforward
Beginning balance			$ (0.8)				(0.8)
Other comprehensive (loss) income							1.1
Ending balance	$ 0.3						$ 0.3