EMPLOYEE BENEFIT PLANS - Components of Net Periodic Benefit Cost (Details) - Defined benefit pension plans - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Defined Benefit Plan Disclosure [Line Items]
Service cost, net	$ 7.9	$ 6.8	$ 7.0
Interest cost	1.0	1.2	1.5
Expected return on plan assets	(2.0)	(1.3)	(1.5)
Settlements and curtailment gain	(6.3)	0.0	0.6
Special termination benefits	0.6	0.0	0.0
Amortization of actuarial loss	0.9	0.7	1.0
Amortization of prior service cost (credit)	0.2	(0.7)	(0.4)
Net periodic pension benefit cost	$ 2.3	$ 6.7	$ 8.2