Summary of Significant Accounting Policies - Additional Information (Details)		3 Months Ended				9 Months Ended		12 Months Ended
	Mar. 27, 2020	Sep. 30, 2021 USD ($) shares	Sep. 30, 2020 USD ($) shares	Jun. 30, 2020 USD ($)	Mar. 31, 2020 USD ($)	Sep. 30, 2021 USD ($) segment shares	Sep. 30, 2020 USD ($) shares	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)
Significant Accounting Policies [Line Items]
Number of Reportable Segments | segment						1
Accounts receivable		$ 22,131,000				$ 22,131,000		$ 9,806,000
Allowance for doubtful accounts		1,700,000				1,700,000
Accounts Receivable, net		23,800,000				23,800,000
Goodwill impairment loss						0		0
Operating Loss Carryforwards		29,800,000				29,800,000
Deferred Tax Assets, Valuation Allowance								$ 19,000,000.0	$ 19,000,000.0	$ 11,300,000
Gross net operating losses		16,300,000				16,300,000
Reduction in valuation allowance		(4,900,000)				$ (4,900,000)
Valuation Allowance, Deferred Tax Asset, Increase (Decrease), Amount		$ 14,100,000
Options and warrants excluded from the calculation of diluted shares | shares		28,276	7,043,259			59,119	7,043,259
State and Local Jurisdiction [Member]
Significant Accounting Policies [Line Items]
Operating Loss Carryforwards		$ 16,500,000				$ 16,500,000
Customer Concentration Risk [Member] | One Customer | Revenue from Contract with Customer [Member]
Significant Accounting Policies [Line Items]
Concentration Risk, Percentage						10.00%	13.00%
Customer Concentration Risk [Member] | One Customer | Accounts Receivable
Significant Accounting Policies [Line Items]
Accounts Receivable, net		$ 3,000,000.0	$ 2,000,000.0			$ 3,000,000.0	$ 2,000,000.0
CARES Act
Significant Accounting Policies [Line Items]
Percent of taxable income offset for taxable years beginning before 2021	100.00%					80.00%
Preliminary tax benefit related to the alternative minimum tax refund					$ 47,000
Additional tax benefit related to the alternative minimum tax refund				$ 380,000