STOCK-BASED COMPENSATION - Summary of Stock options exercised, restricted stock vested, shares withheld and shares issued (Details) - USD ($)	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Number of Shares
Stock compensation expense	$ 1,900,000	$ 2,400,000	$ 1,600,000
Unrecognized compensation expense	$ 3,400,000
Weighted average period	2 years
Stock options
Number of Shares
Stock Options, Exercised/Vested	11,358	15,244
Stock Options, Shares withheld		(2,318)
Stock Options, Shares Issued	11,358	12,926
Non-performance based restricted stock
Number of Shares
Restricted Stock, Exercised/Vested	63,160	61,590
Restricted Stock, Shares withheld	(9,578)	(6,672)
Restricted Stock, Shares Issued	$ 53,582	$ 54,918
Performance-based restricted stock
Number of Shares
Restricted Stock, Exercised/Vested		6,000
Restricted Stock, Shares withheld		(1,463)
Restricted Stock, Shares Issued		$ 4,537

Amount of expense for award under share-based payment arrangement. Excludes amount capitalized.

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