POSTRETIREMENT BENEFITS (Details 3) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Components of Net Periodic Benefit Cost [Abstract]
Service cost	$ 9.1	$ 8.9
Interest cost	86.6	87.7	$ 83.3
Amortization of prior service cost	2.2	0.0	1.6
Curtailment	0.0	0.0	47.2
Net periodic benefit cost	26.4	37.1	(18.7)
Included in Other Comprehensive Loss (Pretax)
Liability adjustment	26.9	66.1	125.4
Amortization of prior service costs and actuarial losses	(26.9)	(20.4)	(65.6)
Other Postretirement Benefit Plans, Defined Benefit
Components of Net Periodic Benefit Cost [Abstract]
Service cost	1.1	1.2	1.2
Interest cost	1.5	1.6	2.3
Amortization of prior service cost	(2.2)	(2.6)	0.0
Recognized actuarial loss	2.1	2.3	3.1
Curtailment	0.0	0.0	0.1
Net periodic benefit cost	(2.5)	(2.5)	(6.7)
Included in Other Comprehensive Loss (Pretax)
Liability adjustment	0.4	(5.1)	(0.1)
Amortization of prior service costs and actuarial losses	$ 0.1	$ 0.3	$ (3.2)