Annual report pursuant to Section 13 and 15(d)

Retirement plans (Details)

v3.20.4
Retirement plans (Details) - USD ($)
12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Retirement Benefits [Abstract]    
Maximum employer annual contribution per employee, percent 4.50%  
Contributions to plan $ 124,507 $ 265,280