BENEFIT PLANS - AMOUNTS RECOGNIZED IN ACCUMULATED OTHER COMPREHENSIVE INCOME (Details) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Pension Plans
Schedule of Pension and Other Postretirment Benefits Recgonized in Accumulated Other Comprehensive Income (Loss) [Line Items]
Net actuarial loss	$ 115.3	$ 100.1
Net prior service cost	(1.8)	(2.4)
Before tax AOCI	113.5	97.7
Less: Deferred taxes	31.2	26.2
Net of tax AOCI	82.3	71.5
Other Postemployment Benefits
Schedule of Pension and Other Postretirment Benefits Recgonized in Accumulated Other Comprehensive Income (Loss) [Line Items]
Net actuarial loss	3.5	2.4
Net prior service cost	0.0	0.0
Before tax AOCI	3.5	2.4
Less: Deferred taxes	1.3	0.9
Net of tax AOCI	$ 2.2	$ 1.5