OTHER INVESTMENTS (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Marketable securities
Amortized Cost	$ 257.9		$ 257.2
Unrealized Gains	7.3		3.0
Unrealized Losses	(0.1)		(0.4)
Fair Value	265.1		259.8
Other Investments, Total
Amortized Cost	257.9		257.2
Unrealized Gains	7.3		3.0
Unrealized Losses	(0.1)		(0.4)
Fair Value	265.1		259.8
Fair Value, Marketable securities
Less than 12 months	3.7		18.8
12 Months or Greater			13.1
Total	3.7		31.9
Unrealized Losses, Marketable securities
Less than 12 months	(0.1)		(0.2)
12 Months or Greater			(0.2)
Total	(0.1)		(0.4)
Fair Value, Total
Less than 12 months	3.7		18.8
12 Months or Greater			13.1
Total	3.7		31.9
Unrealized Losses, Total
Less than 12 months	(0.1)		(0.2)
12 Months or Greater			(0.2)
Total	(0.1)		$ (0.4)
Amortized Cost
Due in one year or less	40.2
Due after one year through five years	1.4
Due after ten years	216.3
Total	257.9
Fair Value
Due in one year or less	40.2
Due after one year through five years	1.4
Due after ten years	223.5
Fair Value	265.1
Realized gains or losses
Realized gains or losses from the sale of investment securities	$ 0.0	$ 0.0