SUMMARY OF ACCOUNTING POLICIES - Basic and diluted earnings per common share (Details) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Numerator for basic and diluted (loss) earnings per common share:
Net (loss) income	$ (4,954,000)	$ 4,911,000
Denominator:
Denominator for basic (loss) income per share-weighted average common shares outstanding	3,149,000	3,207,000
Dilutive securities		55,000
Denominator for diluted (loss) income per share-adjusted weighted average common shares and assumed conversions	3,149,000	3,262,000