LEASES - LEASE EXPENSE AND SUPPLEMENTAL CASH FLOW INFORMATION (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Lease expense
Operating lease expense	$ 1.4	$ 1.4	$ 2.8	$ 2.8
Short-term lease expense	0.1	0.6	0.1	0.7
Lease expense	3.6	3.9	7.0	7.3
Amortization of finance lease right of use assets	1.2		2.3
Interest on finance lease liabilities	$ 0.9		1.8
Other information
Operating cash flows from finance/capital lease			1.8	3.8
Operating cash flows from operating leases			3.2	3.3
Financing cash flows from finance lease			2.3	0.0
Noncash activity - right of use assets obtained in exchange for new operating lease liabilities			$ 49.0
Remaining lease term - finance lease	2 years 10 months 24 days		2 years 10 months 24 days
Weighted average remaining lease term - operating leases	13 years 1 month 6 days		13 years 1 month 6 days
Discount rate - finance lease	15.80%		15.80%
Weighted average discount rate - operating leases	4.40%		4.40%
Finance and capital leases
Lease expense
Lease expense	$ 2.1	$ 1.9	$ 4.1	$ 3.8