LEASES - Lease Cost (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Leases [Abstract]
Operating lease cost	$ 24.2
Operating lease cost		$ 23.4	$ 20.7
Amortization of leased assets	11.6
Amortization of leased assets		18.4	12.4
Interest on lease liabilities	2.6
Interest on lease liabilities		2.1	1.6
Total finance lease cost	14.2
Total finance lease cost		20.5	14.0
Total	38.4
Total		$ 43.9	$ 34.7
Short-term lease and variable lease costs	$ 5.9