PROPERTY, PLANT AND EQUIPMENT - Schedule of Property, Plant, and Equipment (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 66.4	$ 62.5
Less accumulated depreciation and amortization	51.3	46.1
Property, plant and equipment, net	15.1	16.4
SARL Business Segment
Property, Plant and Equipment [Line Items]
Property, plant and equipment, net		13.1
Land improvements
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	0.8	0.8
Furniture and fixtures, office, computer and other equipment and software
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	48.8	47.1
Leasehold improvements
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 16.8	14.6
Assets Held under Capital Leases | SARL Business Segment
Property, Plant and Equipment [Line Items]
Property, plant and equipment, net		$ 0.2