INTERIM FINANCIAL STATEMENTS (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017	Dec. 31, 2016
CONDENSED STATEMENTS OF INCOME AND COMPREHENSIVE INCOME:
Revenue	$ 19,017,301	$ 20,706,460	$ 57,470,163	$ 57,471,112
Gross profit	3,871,221	4,912,436	12,505,907	13,133,698
Net income	585,896	1,695,513	3,099,886	3,710,461
Comprehensive income	$ 606,496	$ 1,693,213	$ 3,114,686	$ 3,712,361
Earnings per common share - basic (in dollars per share)	$ 0.07	$ 0.19	$ 0.35	$ 0.42
Earnings per common share - diluted (in dollars per share)	$ 0.07	$ 0.19	$ 0.35	$ 0.42
CONDENSED STATEMENT OF SHAREHOLDERS' EQUITY:
Total shareholders' equity	$ 78,010,102	$ 72,105,357	$ 78,010,102	$ 72,105,357	$ 74,313,333	$ 67,605,706
Previously Reported [Member]
CONDENSED STATEMENTS OF INCOME AND COMPREHENSIVE INCOME:
Revenue	19,944,558		58,397,420
Gross profit	4,798,478		13,433,164
Net income	1,328,153		3,842,143
Comprehensive income	1,348,753		$ 3,856,943
Earnings per common share - basic (in dollars per share)			$ 0.43
Earnings per common share - diluted (in dollars per share)			$ 0.43
CONDENSED STATEMENT OF SHAREHOLDERS' EQUITY:
Total shareholders' equity	78,752,359		$ 78,752,359
Adjustment [Member]
CONDENSED STATEMENTS OF INCOME AND COMPREHENSIVE INCOME:
Revenue	927,257		927,257
Gross profit	927,257		927,257
Net income	742,257		742,257
Comprehensive income	742,257		$ 742,257
Earnings per common share - basic (in dollars per share)			$ 0.08
Earnings per common share - diluted (in dollars per share)			$ 0.08
CONDENSED STATEMENT OF SHAREHOLDERS' EQUITY:
Total shareholders' equity	$ 742,257		$ 742,257