General form of registration statement for all companies including face-amount certificate companies

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Details)

v3.20.4
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Details)
$ in Thousands
 9 Months Ended 12 Months Ended
Sep. 30, 2020
USD ($)
item
Sep. 30, 2019
USD ($)
Dec. 31, 2019
USD ($)
item
Dec. 31, 2018
USD ($)
Significant Accounting Policies [Line Items]        
Money market funds $ 33,900   $ 40,500 $ 24,000
Other highly liquid cash equivalents 0   25,000  
Deferred revenue from sales to investors 1,100   2,200 3,900
Deferred revenue recognized     3,900  
Deferred cost of sales 0   300 3,000
Allowance for doubtful accounts 500   200 0
Bad debt expense $ 300 $ 0 $ 200 0
Number of customers represents more than 10% of total accounts receivable | item 1   0  
Transaction costs payable $ 2,300      
Warranty reserve 1,734   $ 1,491 116
Sales and marketing expense        
Significant Accounting Policies [Line Items]        
Advertising Expense     100 100
Accounts Payable        
Significant Accounting Policies [Line Items]        
Transaction costs payable 1,700      
Accrued expenses and other current liabilities        
Significant Accounting Policies [Line Items]        
Transaction costs payable $ 600      
Warranty reserve     1,500 $ 100
Restricted Cash        
Significant Accounting Policies [Line Items]        
Security deposit     $ 600