Debt - Narrative (Details) - USD ($)			12 Months Ended		18 Months Ended
	Jan. 15, 2018	Feb. 17, 2016	Dec. 31, 2018	Dec. 31, 2017	Jun. 30, 2020
Debt Instrument [Line Items]
Unamortized debt issuance costs			$ 5,000
Unamortized discount			69,000
Long-term debt			4,925,000	$ 4,855,000
Interest paid			$ 572,000	$ 611,000
Hercules Technology Growth Capital | Secured Debt | Loans Payable
Debt Instrument [Line Items]
Loan facility		$ 10,000,000
Initial draw amount		6,000,000
Proceeds net of issuance costs		$ 5,839,000
Debt payments deferred, consecutive period	13 months
Hercules Technology Growth Capital | Secured Debt | Loans Payable | Prime Rate
Debt Instrument [Line Items]
Floating interest rate (as a percent)		9.95%
Reduction of prime rate (as a percent)		3.50%
Series C | Hercules Technology Growth Capital | Secured Debt | Loans Payable
Debt Instrument [Line Items]
Shares issuable on debt instrument (in shares)		80,000
Exercise price (in dollars per share)		$ 3
Preferred stock warrant liability		$ 134,000
Unamortized discount		$ 134,000
Minimum | Hercules Technology Growth Capital | Secured Debt | Loans Payable
Debt Instrument [Line Items]
Interest rate, stated percentage		9.95%
Fees at Issuance | Hercules Technology Growth Capital | Secured Debt | Loans Payable
Debt Instrument [Line Items]
Unamortized debt issuance costs		$ 161,000
Fees at Maturity | Hercules Technology Growth Capital | Secured Debt | Loans Payable
Debt Instrument [Line Items]
Unamortized debt issuance costs		$ 231,000
Scenario, Forecast | Hercules Technology Growth Capital | Secured Debt | Loans Payable
Debt Instrument [Line Items]
Amortization of principal and interest, consecutive period					18 months