BENEFIT PLANS - COMPONENTS OF NET PERIODIC BENEFIT COST (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Defined Benefit Plans
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost	$ 3.9	$ 3.9	$ 7.7	$ 7.7
Interest cost	1.8	2.0	3.5	3.8
Expected return on plan assets	(1.2)	(1.2)	(2.3)	(2.4)
Amortization of prior service credit	(0.1)	(0.1)	(0.1)	(0.1)
Amortization of net actuarial loss	1.7	1.3	3.3	2.5
Net periodic benefit cost	6.1	5.9	12.1	11.5
Other Postemployment Benefit Plans
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost	0.1	0.1	0.2	0.2
Interest cost	0.1	0.1	0.2	0.3
Amortization of net actuarial loss	0.0	0.1	0.1	0.1
Net periodic benefit cost	$ 0.2	$ 0.3	$ 0.5	$ 0.6