PENSION AND POST-RETIREMENT PLANS - AMOUNTS INCLUDED IN FINANCIAL STATEMENTS (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Employee benefit plans
Non-current liabilities, net	$ (108.5)	$ (109.3)
Pensions
Employee benefit plans
Non-current assets	1.0
Non-current liabilities, net	(47.6)	(51.3)
Total	(46.6)	(51.3)
Net loss, net of taxes	(49.1)	(50.8)
Prior service credit (net of taxes)	7.7	9.1
Total	(41.4)	(41.7)
Benefit obligation	225.4	220.2	$ 237.4
Fair value of plan assets at end of year	178.8	168.9	178.9
Estimated net loss and prior service credit that will be amortized from accumulated other comprehensive loss into net periodic benefit cost in 2017	1.7
Other Post-retirement Benefits
Employee benefit plans
Current liabilities	(2.7)	(2.5)
Non-current liabilities, net	(60.9)	(58.0)
Total	(63.6)	(60.5)
Net loss, net of taxes	(4.4)	(4.7)
Total	(4.4)	(4.7)
Benefit obligation	63.6	60.5	$ 62.6
Nonqualified Pensions Benefits
Employee benefit plans
Current liabilities	(1.0)	(1.2)
Non-current liabilities, net	(3.3)	(3.1)
Total	(4.3)	(4.3)
Net loss, net of taxes	(0.8)	(0.8)
Prior service credit (net of taxes)	0.4	0.6
Total	(0.4)	(0.2)
Estimated net loss and prior service credit that will be amortized from accumulated other comprehensive loss into net periodic benefit cost in 2017	0.1
Post Retirement
Employee benefit plans
Estimated net loss and prior service credit that will be amortized from accumulated other comprehensive loss into net periodic benefit cost in 2017	$ 0.9
Amortization period of unrecognized gains and losses	5 years
Qualified Pension Plans
Employee benefit plans
Benefit obligation	$ 223.2	218.0
Accumulated benefit obligation	222.9	217.7
Fair value of plan assets at end of year	$ 175.9	$ 166.2