STOCK-BASED COMPENSATION - Valuation Assumptions and Other Information (Details) - Stock options - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Option valuation assumptions for options granted
Weighted average expected volatility for options granted (as a percent)	40.87%	30.13%	32.98%
Weighted average risk free rate (as a percent)	0.48%	1.83%	2.76%
Weighted average grant date fair value per share of options granted (in dollars per share)	$ 17.33	$ 12.19	$ 13.52
Total fair value of shares vested	$ 3,852	$ 2,407	$ 2,080
Total intrinsic value of options exercised	15,258	5,932	4,659
Cash received for all stock option exercises	7,813	4,060	2,354
Tax benefit realized from stock awards exercised	$ 3,204	$ 1,246	$ 978
Directors
Option valuation assumptions for options granted
Expected life	3 years 3 months 3 days	3 years 14 days	3 years 14 days
Executives
Option valuation assumptions for options granted
Expected life	5 years 2 months 19 days	5 years 25 days	5 years 25 days
Employees
Option valuation assumptions for options granted
Expected life	4 years 1 month 17 days	4 years 2 months 4 days	4 years 1 month 13 days