PROPERTY AND EQUIPMENT - Summary of depreciation expense (Details 1) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Property, Plant and Equipment [Line Items]
Depreciation expense	$ 178,262	$ 63,062	$ 287,682	$ 120,263
Cost of revenues
Property, Plant and Equipment [Line Items]
Depreciation expense	134,629	45,266	216,062	85,703
Selling, general and administrative expenses
Property, Plant and Equipment [Line Items]
Depreciation expense	$ 43,633	$ 17,796	$ 71,620	$ 34,560