STOCK-BASED COMPENSATION PLANS - Unrecognized stock-based compensation expense and stock option exercises (Details) - Stock Options - USD ($) shares in Thousands, $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Unrecognized stock-based compensation expense and stock option exercises
Unrecognized stock-based compensation expense related to non-vested stock options	$ 5.6
Weighted-average period over which unrecognized expense	3 years 2 months 12 days
Total fair value of stock options vested	$ 2.7	$ 2.5	$ 2.5
Proceeds from stock option exercises	3.2	14.2
Related tax benefits from stock option exercises	$ 0.3	$ 1.8
Shares issued in connection with stock option exercise (in shares)	60	300
Total intrinsic value of options exercised	$ 2.0	$ 10.3	$ 6.6