Quarterly report pursuant to Section 13 or 15(d)

Long-Term Debt - Additional Information (Details)

v3.21.2
Long-Term Debt - Additional Information (Details) - Promissory Notes Payable
$ in Thousands
9 Months Ended 12 Months Ended
Sep. 30, 2021
USD ($)
Dec. 31, 2019
Dec. 31, 2020
USD ($)
Jan. 01, 2019
USD ($)
Installment
Debt Instrument [Line Items]        
Debt instrument, outstanding balance | $ $ 251   $ 362 $ 736
Debt instrument, periodic payment, number of equal quarterly installments | Installment       20
Debt instrument, frequency of periodic payment   quarterly    
Minimum        
Debt Instrument [Line Items]        
Debt instrument, payment term 2 years      
Maximum        
Debt Instrument [Line Items]        
Debt instrument, payment term 4 years      
Interest rate, stated percentage 8.00%