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)

v3.20.1
Nature of business and summary of significant accounting policies, Accounts receivable and allowance for doubtful accounts (Details) - USD ($)
$ in Millions
Dec. 31, 2019
Dec. 31, 2018
Accounts receivable and allowance for doubtful accounts [Abstract]    
Allowance for doubtful accounts   $ 0.0
Maximum [Member]    
Accounts receivable and allowance for doubtful accounts [Abstract]    
Allowance for doubtful accounts $ 0.1