STOCK-BASED COMPENSATION PLANS, Unrecognized Stock-Based Compensation Expense and Stock Option Exercises (Details) - Stock Options [Member] - USD ($) shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized stock-based compensation expense related to non-vested stock options	$ 4.6
Weighted average period for recognition of unrecognized compensation cost	3 years 2 months 12 days
Total fair value of stock options vested	$ 2.2	$ 2.1	$ 1.9
Proceeds from stock option exercises	7.7	12.0
Related tax benefits from stock option exercises	$ 2.3	$ 2.7
Shares issued in connection with stock option exercise (in shares)	0.2	0.4
Total intrinsic value of options exercised	$ 7.6	$ 10.3	$ 7.6