STOCK-BASED COMPENSATION PLANS - Unrecognized stock-based compensation expense and stock option exercises (Details) - Remaining Stock Options [Member] - USD ($) shares in Thousands, $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Unrecognized Stock-Based Compensation Expense and Stock Option Exercises
Unrecognized stock-based compensation expense related to non-vested stock options	$ 6.3
Weighted average period for recognition of unrecognized compensation cost	3 years 1 month 6 days
Total fair value of stock options vested	$ 2.7	$ 2.7	$ 2.5
Proceeds from stock option exercises	2.6	$ 3.2
Related tax benefits from stock option exercises	$ 0.3
Shares issued in connection with stock option exercise (in shares)	70	60
Total intrinsic value of options exercised	$ 1.7	$ 2.0	$ 10.3