Loan and Security Agreements - Narrative (Details)			3 Months Ended			9 Months Ended
	Jul. 14, 2020 USD ($)	Jul. 19, 2019 USD ($) tranche	Jan. 15, 2021 USD ($)	Sep. 30, 2020 USD ($)	Sep. 30, 2019 USD ($)	Sep. 30, 2020 USD ($)	Sep. 30, 2019 USD ($)
Line of Credit Facility [Line Items]
Proceeds from Issuance of Long-term Debt						$ 10,000,000	$ 19,481,000
2016 Credit Facility
Line of Credit Facility [Line Items]
Aggregate principal amount				$ 15,000,000.0		15,000,000.0
Interest expense							500,000
2019 Credit Facility
Line of Credit Facility [Line Items]
Interest expense				600,000	$ 400,000	1,500,000	$ 400,000
Line of Credit | 2016 Credit Facility
Line of Credit Facility [Line Items]
Aggregate principal amount				$ 15,000,000.0		$ 15,000,000.0
Line of Credit | 2019 Credit Facility
Line of Credit Facility [Line Items]
Aggregate principal amount		$ 45,000,000.0
Number of tranches | tranche		3
Loan and security agreement, interest rate		8.65%
Final payment under agreement as a percentage of loans borrowed		4.30%
Fees incurred to establish facility		$ 400,000
Prepayment fee percentage		2.00%
Anniversary of funding date for determining prepayment fee percentage		18 months
Prepayment fee percentage after specified period		1.00%
Debt default interest rate per annum		5.00%
Line of Credit | Security And Loan Agreement, Tranche One | 2019 Credit Facility
Line of Credit Facility [Line Items]
Proceeds from Issuance of Long-term Debt		$ 20,000,000.0
Line of Credit | Security And Loan Agreement, Tranche Two | 2019 Credit Facility
Line of Credit Facility [Line Items]
Proceeds from Issuance of Long-term Debt	$ 10,000,000.0
Line of Credit | Security And Loan Agreement, Tranche Three | 2019 Credit Facility | Forecast
Line of Credit Facility [Line Items]
Proceeds from Issuance of Long-term Debt			$ 15,000,000.0
Line of Credit | Prime Plus | 2019 Credit Facility
Line of Credit Facility [Line Items]
Loan and security agreement, basis spread on interest rate		3.15%