STOCKHOLDERS' EQUITY - Reconciliation of Changes (Details) - USD ($)	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance, beginning of period	$ 45,255,859	$ 44,047,424
Stock based compensation	66,714	390,585
Stock issued in exercise of stock options	0	258,892
Stock issued in settlement of RSUs	0	0
Stock issued related to AIP	379,861
Tax withholdings paid related to stock based compensation	(143,022)	(83,600)
Treasury stock repurchased	(1,333,578)	0
Foreign currency translation gain (loss)	149,415	(239,129)
Unrealized gains on investments	68,752	(33,235)
Net income	1,668,618	1,876,228
Balance, end of period	$ 46,112,619	$ 46,217,165
Common Stock
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance, beginning of period (shares)	47,932,305	48,606,425
Balance, beginning of period	$ 49,708	$ 53,931
Stock issued in exercise of stock options (shares)	2,483	81,229
Stock issued in exercise of stock options	$ 2	$ 81
Stock issued in settlement of RSUs (shares)	13,604	118,762
Stock issued in settlement of RSUs	$ 14	$ 119
Stock issued related to AIP (shares)	135,119
Stock issued related to AIP	$ 135
Treasury stock repurchased (shares)	(775,287)
Balance, end of period (shares)	47,308,224	48,806,416
Balance, end of period	$ 49,859	$ 54,131
Additional Paid-In Capital
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance, beginning of period	28,027,742	27,535,469
Stock based compensation	66,714	390,585
Stock issued in exercise of stock options	(2)	258,811
Stock issued in settlement of RSUs	(14)	(119)
Stock issued related to AIP	379,726
Tax withholdings paid related to stock based compensation	(143,022)	(83,600)
Balance, end of period	28,331,144	28,101,146
Accumulated Other Comprehensive Income (Loss)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance, beginning of period	(2,895,683)	(2,200,462)
Foreign currency translation gain (loss)	149,415	(239,129)
Unrealized gains on investments	68,752	(33,235)
Balance, end of period	(2,677,516)	(2,472,826)
Treasury Stock
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance, beginning of period	(2,609,485)	(6,890,349)
Treasury stock repurchased	(1,333,578)
Balance, end of period	(3,943,063)	(6,890,349)
Retained Earnings
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance, beginning of period	22,683,577	25,548,835
Net income	1,668,618	1,876,228
Balance, end of period	$ 24,352,195	$ 27,425,063