STOCK OPTIONS - Summary of Stock Options (Details) - $ / shares	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Number of options and warrants
Outstanding, beginning of period (in shares)	3,254,779	4,634,235	3,526,287
Granted (in shares)	1,379,500	225,000	1,728,000
Exercised (in shares)	(410,635)	(1,378,615)	(176,750)
Cancelled and forfeited (in shares)	(256,785)	(225,841)	(443,302)
Outstanding, end of period (in shares)	3,966,858	3,254,779	4,634,235
Weighted average exercise price
Outstanding, beginning of period (in dollars per share)	$ 3.18	$ 3.10	$ 3.17
Granted (in dollars per share)	7.70	2.40	3.09
Exercised (in dollars per share)	2.99	2.43	2.41
Cancelled and forfeited (in dollars per share)	4.76	2.10	3.95
Outstanding, end of period (in dollars per share)	$ 4.67	$ 3.18	$ 3.10