ACCOUNTS RECEIVABLE AND CUSTOMER DEPOSITS - Customer deposit liability (Details)	6 Months Ended
	Jun. 30, 2020 USD ($)
Changes in deferred revenue and customer deposit liability
January 1, 2020	$ 562,803
Additional deposits received	2,442,129
Less: Deposits recognized as revenue	(2,584,551)
Less: Refunds to customers	(80,600)
June 30, 2020	$ 339,781