LEASES - Components of assets and liabilities (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Components of assets and liabilities for operating and finance leases
Right-of-use assets	$ 121.1	$ 95.9
Operating Lease, Right-of-Use Asset, Statement of Financial Position [Extensible List]	Right-of-use assets	Right-of-use assets
Finance lease right-of-use assets	$ 30.6	$ 25.3
Finance Lease, Right-of-Use Asset, Statement of Financial Position [Extensible List]	Property, Plant and Equipment, Net	Property, Plant and Equipment, Net
Total lease assets	$ 151.7	$ 121.2
Current	$ 30.9	$ 27.3
Operating Lease, Liability, Current, Statement of Financial Position [Extensible List]	Current	Current
Non-current	$ 96.0	$ 77.8
Operating Lease, Liability, Noncurrent, Statement of Financial Position [Extensible List]	Non-current	Non-current
Total operating lease liabilities	$ 126.9	$ 105.1
Current	$ 8.5	$ 6.2
Finance Lease, Liability, Current, Statement of Financial Position [Extensible List]	Long-term Debt, Current Maturities	Long-term Debt, Current Maturities
Non-current	$ 22.7	$ 19.3
Finance Lease, Liability, Noncurrent, Statement of Financial Position [Extensible List]	Long Term Debt Excluding Line Of Credit Noncurrent	Long Term Debt Excluding Line Of Credit Noncurrent
Total finance lease liabilities	$ 31.2	$ 25.5
Total lease liabilities	158.1	130.6
Operating cash flows from operating leases	(37.8)	(35.6)
Operating cash flows from finance leases	(1.1)	(0.9)
Financing cash flows from finance leases	(6.6)	(5.9)
Operating lease right-of-use assets	54.6	39.2
Finance lease right-of-use assets	$ 11.6	$ 13.1