STOCK-BASED COMPENSATION - Status of Nonvested Shares and Unrecognized Costs (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Unrecognized costs
Unrecognized costs related to all share-based awards outstanding	$ 10.3
Weighted average period for recognition of unrecognized compensation costs	2 years 4 months 24 days
Stock options
Nonvested Stock Option Shares
Nonvested at the beginning of the period (in shares)	1,229,651
Granted (in shares)	428,298
Vested (in shares)	(338,328)
Forfeited (in shares)	(141,667)
Nonvested at the end of the period (in shares)	1,177,954	1,229,651
Weighted-Average Grant Date Fair Value
Nonvested at the beginning of the period (in dollars per share)	$ 12.37
Granted (in dollars per share)	17.33	$ 12.19	$ 13.52
Vested (in dollars per share)	11.38
Forfeited (in dollars per share)	12.11
Nonvested at the end of the period (in dollars per share)	$ 14.49	$ 12.37