Debt - Narrative (Details)	Oct. 29, 2021 USD ($)	Jun. 27, 2019 USD ($)	Oct. 30, 2018 USD ($) covenant	Sep. 30, 2021 USD ($)	Dec. 31, 2020 USD ($)	May 31, 2020 USD ($)	Dec. 31, 2019 USD ($)
Debt Instrument [Line Items]
Long-term debt				$ 0	$ 6,927,000
2018 Term Notes
Debt Instrument [Line Items]
Repayments of long-term debt		$ 21,375,000
PPP Loan
Debt Instrument [Line Items]
Long-term debt				0	$ 6,927,000	$ 6,927,000
Line of Credit | Senior Credit Facility | 2018 Term Notes
Debt Instrument [Line Items]
Credit facility term			3 years
Maximum available for borrowing			$ 42,500,000
Line of Credit | Senior Credit Facility | Term Loan
Debt Instrument [Line Items]
Maximum available for borrowing			22,500,000
Line of Credit | Senior Credit Facility | Revolving Credit Facility
Debt Instrument [Line Items]
Long-term debt				0
Maximum available for borrowing			$ 20,000,000	$ 15,000,000			$ 15,000,000
Repayments of line of credit borrowings		$ 13,000,000
Line of Credit | Senior Credit Facility | Revolving Credit Facility | Subsequent Event
Debt Instrument [Line Items]
Maximum available for borrowing	$ 15,000,000
Covenant compliance, minimum trailing twelve month Consolidated Adjusted EBITDA	$ 3,000,000
Line of Credit | Senior Credit Facility | Line of Credit
Debt Instrument [Line Items]
Number of financial covenants | covenant			2
Covenant compliance, maximum consolidated fixed charge coverage ratio			1.25
Line of Credit | Senior Credit Facility | Line of Credit | Debt Covenant Period, One
Debt Instrument [Line Items]
Covenant compliance, maximum consolidated leverage ratio			2.50
Line of Credit | Senior Credit Facility | Line of Credit | Debt Covenant Period, Two
Debt Instrument [Line Items]
Covenant compliance, maximum consolidated leverage ratio			2.00