BENEFIT PLANS - AMOUNTS RECOGNIZED IN ACCUMULATED OTHER COMPREHENSIVE INCOME (Details) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Pension Plans, Defined Benefit
Schedule of Pension and Other Postretirment Benefits Recgonized in Accumulated Other Comprehensive Income (Loss) [Line Items]
Net actuarial loss	$ 100.1	$ 156.4
Net prior service cost	(2.4)	(2.2)
Before tax AOCI	97.7	154.2
Less: Deferred taxes	26.2	42.4
Net of tax AOCI	71.5	111.8
Other Postretirement Benefit Plans, Defined Benefit
Schedule of Pension and Other Postretirment Benefits Recgonized in Accumulated Other Comprehensive Income (Loss) [Line Items]
Net actuarial loss	2.4	3.0
Net prior service cost	0.0	0.0
Before tax AOCI	2.4	3.0
Less: Deferred taxes	0.9	1.2
Net of tax AOCI	$ 1.5	$ 1.8