CUSTOMER DEPOSITS - Customer Deposit Liability (Details)	3 Months Ended
Mar. 31, 2021 USD ($)
Changes in deferred revenue and customer deposit liability
Balance, beginning of year	$ 517,931
Additional deposits received	321,772
Less: Deposits recognized as revenue	(763,797)
Balance, end of year	$ 75,906

Amount of deferred income and obligation to transfer product and service to customer for which consideration has been received or is receivable, classified as current.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(5))
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

Name:	us-gaap_DeferredRevenueCurrent
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant