SHARE-BASED AWARDS - Summary of Compensation Cost Related to Share-based Payments (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total share-based expense	$ 4.1	$ 4.6	$ 4.9
Total recognized tax benefit	(1.4)	(1.2)	(1.5)
Share-based expense (net of tax)	2.7	3.4	3.4
Cash received upon option exercise	4.6	0.5	4.5
Intrinsic value of options exercised	2.6	0.5	5.4
Tax benefit realized upon option exercise	1.0	0.2	2.0
Fair value of stock vested	2.2	4.2	2.6
Stock options
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total share-based expense	0.0	0.0	0.3
Incremental share-based compensation cost related to separation
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total share-based expense	0.0	0.0	0.2
Time-based and market-based restricted stock units
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total share-based expense	$ 4.1	$ 4.6	$ 4.4