SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Property and Equipment (Details)	3 Months Ended
	Mar. 31, 2021
Computer equipment
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	3 years
Tooling
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	3 years
Minimum | Equipment
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	2 years
Minimum | Furniture and fixtures
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	3 years
Minimum | Software
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	2 years
Maximum | Equipment
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	12 years
Maximum | Software
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	3 years