PENSION AND POST-RETIREMENT PLANS - AMOUNTS INCLUDED IN FINANCIAL STATEMENTS (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Employee benefit plans
Current liabilities	$ (2.5)	$ (2.5)
Non-current liabilities, net	(109.3)	(118.6)
Qualified Pension Benefits
Employee benefit plans
Non-current liabilities, net	(51.3)	(58.5)
Total	(51.3)	(58.5)
Net loss (net of taxes)	50.8	55.5
Prior service credit (net of taxes)	(9.1)	(10.6)
Total	41.7	44.9
Benefit obligation	220.2	237.4	$ 197.5
Fair value of plan assets at end of year	168.9	178.9	172.8
Estimated net loss and prior service credit that will be amortized from accumulated other comprehensive loss into net periodic benefit cost in 2016	1.8
Post-retirement Benefits
Employee benefit plans
Current liabilities	(2.5)	(2.5)
Non-current liabilities, net	(58.0)	(60.1)
Total	(60.5)	(62.6)
Net loss (net of taxes)	4.7	7.2
Total	4.7	7.2
Benefit obligation	60.5	62.6	$ 52.1
Estimated net loss and prior service credit that will be amortized from accumulated other comprehensive loss into net periodic benefit cost in 2016	$ 0.8
Amortization period of unrecognized gains and losses	5 years
Qualified Plans
Employee benefit plans
Benefit obligation	$ 218.0	235.0
Accumulated benefit obligation	217.7	234.6
Fair value of plan assets at end of year	$ 166.2	$ 176.1