Annual report pursuant to Section 13 and 15(d)

Nature of business and summary of significant accounting policies - Accounts receivable and allowance for doubtful accounts (Details)

v3.21.1
Nature of business and summary of significant accounting policies - Accounts receivable and allowance for doubtful accounts (Details) - USD ($)
Dec. 31, 2020
Dec. 31, 2019
Accounting Policies [Abstract]    
Allowance for doubtful accounts $ 100,000 $ 100,000