Summary of Significant Accounting Policies - Loan Facility Derivative Liability (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021 USD ($)	Sep. 30, 2020 USD ($)	Sep. 30, 2021 USD ($)	Sep. 30, 2020 USD ($)
Loan Facility
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Trailing twelve month revenue target			$ 200,000
Fee on first installment drawn	$ 1,000		1,000
Fee if first two installments drawn	2,000		2,000
Fee if first three installments drawn	2,400		2,400
Fee if all four installments are drawn	3,000		3,000
Derivative liability, loan facility	1,400		1,400
Fair Value, Inputs, Level 3 | Fair Value, Measurements, Recurring
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Beginning of the period	1,787	$ 1,698	1,782	$ 1,482
Issued	0	0	0	0
Change in fair value	(177)	(175)	(172)	41
Payment of success fee	0	0	0	0
End of the period	$ 1,610	$ 1,523	$ 1,610	$ 1,523
Fair Value, Inputs, Level 3 | Valuation Technique, Discounted Cash Flow | Fair Value, Measurements, Recurring
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Cash flow discount	0.10		0.10