OTHER ASSETS (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2020
Other Assets [Abstract]
Supply contracts	$ 1,106.2		$ 1,165.7	$ 1,122.9
Other	64.8		39.6	68.4
Other assets	1,171.0		1,205.3	$ 1,191.3
Equity Method Investments and Joint Ventures [Abstract]
2020 Supply Contract Payment		$ 461.0
2020 Supply Contract Payment Accretion Expense			4.0
Amortization of Supply Contracts	$ 17.5		$ 22.3