STOCK-BASED COMPENSATION - Valuation Assumptions and Other Information (Details) - Stock options - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Option valuation assumptions for options granted
Weighted average expected volatility for options granted (as a percent)	30.13%	32.98%	35.54%
Weighted average risk free rate (as a percent)	1.83%	2.76%	1.83%
Weighted average grant date fair value per share of options granted (in dollars per share)	$ 12.19	$ 13.52	$ 11.92
Total fair value of shares vested	$ 2,407	$ 2,080	$ 1,324
Total intrinsic value of options exercised	5,932	4,659	5,819
Cash received for all stock option exercises	4,060	2,354	5,813
Tax benefit realized from stock awards exercised	$ 1,246	$ 978	$ 2,037
Directors
Option valuation assumptions for options granted
Expected life	3 years 15 days	3 years 15 days	2 years 11 months 27 days
Executives
Option valuation assumptions for options granted
Expected life	5 years 26 days	5 years 26 days	5 years 18 days
Employees
Option valuation assumptions for options granted
Expected life	4 years 2 months 5 days	4 years 1 month 13 days	4 years 1 month 21 days