Loan and Security Agreements - Narrative (Details)		1 Months Ended	3 Months Ended		24 Months Ended
	Jul. 19, 2019 USD ($) tranche	Feb. 28, 2018 USD ($) $ / shares shares	Mar. 31, 2020 USD ($) payment	Mar. 31, 2019 USD ($)	Dec. 31, 2017 USD ($)	May 31, 2018 USD ($)
2016 Credit Facility
Line of Credit Facility [Line Items]
Aggregate principal amount			$ 15,000,000.0
Credit facility, additional amount borrowed		$ 5,000,000.0			$ 10,000,000.0
Number of monthly payments | payment			24
Interest expense				$ 200,000
2019 Credit Facility
Line of Credit Facility [Line Items]
Interest expense			$ 400,000
Line of Credit
Line of Credit Facility [Line Items]
Success fee		$ 300,000				$ 300,000
Line of Credit | 2016 Credit Facility
Line of Credit Facility [Line Items]
Aggregate principal amount			$ 15,000,000.0
Loan and security agreement, interest rate		4.50%
Prepayment fee percentage		2.00%
Prepayment fee percentage after specified period		0.50%
Line of Credit | 2019 Credit Facility
Line of Credit Facility [Line Items]
Aggregate principal amount	$ 45,000,000.0
Loan and security agreement, interest rate	8.65%
Prepayment fee percentage	2.00%
Prepayment fee percentage after specified period	1.00%
Number of tranches | tranche	3
Final payment under agreement as a percentage of loans borrowed	4.30%
Fees incurred to establish facility	$ 400,000
Anniversary of funding date for determining prepayment fee percentage	18 months
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
Line of Credit Facility [Line Items]
Proceeds from Issuance of Long-term Debt	$ 15,000,000.0
Line of Credit | Prime Plus | 2016 Credit Facility
Line of Credit Facility [Line Items]
Loan and security agreement, basis spread on interest rate		0.25%
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%
Series B Preferred Stock
Line of Credit Facility [Line Items]
Number of shares called by warrants (in shares) | shares		34,722
Warrants exercise price per share (in dollars per share) | $ / shares		$ 1.80