EMPLOYEE BENEFITS - Schedule of Net Periodic Benefit Cost (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost — benefits earned during the period	$ 2.9	$ 4.8	$ 5.2
Interest cost on projected benefit obligations	13.0	15.8	14.4
Expected return on pension plan assets	(14.7)	(15.7)	(17.1)
Amortization of prior service/(benefit)	0.0	0.0	0.0
Amortization of transition cost	0.1	0.1	0.1
Sub-total	1.3	5.0	2.6
Curtailments	0.0	(5.4)	0.0
Net actuarial (gains)/losses	13.7	39.7	(8.2)
Total Pension and Other Post-Employment Benefit costs	15.0	39.3	(5.6)
Other Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost — benefits earned during the period	1.3	0.9	1.1
Interest cost on projected benefit obligations	2.0	1.5	1.3
Expected return on pension plan assets	0.0	0.0	0.0
Amortization of prior service/(benefit)	0.0	0.2	(0.2)
Amortization of transition cost	0.0	0.0	0.0
Sub-total	3.3	2.6	2.2
Curtailments	0.0	0.0	0.0
Net actuarial (gains)/losses	(5.5)	17.2	(3.8)
Total Pension and Other Post-Employment Benefit costs	$ (2.2)	$ 19.8	$ (1.6)