Debt Facilities - Senior Credit Facility - Additional Information (Details) - USD ($)	Aug. 17, 2018	Mar. 05, 2018	Dec. 31, 2018
Line Of Credit Facility [Line Items]
Term loan and equipment advance outstanding amount			$ 23,667,000
Equipment Term Loan Facility
Line Of Credit Facility [Line Items]
Amount of outstanding borrowings		$ 1,100,000
General Corporate Purposes
Line Of Credit Facility [Line Items]
Amount available for borrowings		11,000,000
Term Loan
Line Of Credit Facility [Line Items]
Term loan		20,000,000
Amount of outstanding borrowings		$ 7,900,000
Line of credit facility, amortization period		36 months
Line of credit facility, mature date		Mar. 01, 2022
Term Loan | Term Loan Prepaid On or Before March 5, 2019
Line Of Credit Facility [Line Items]
Percentage of prepayment fee		2.00%
Term Loan | Term Loan Prepaid After March 5, 2019, But On or Before March 5, 2020
Line Of Credit Facility [Line Items]
Percentage of prepayment fee		1.00%
Line of Credit
Line Of Credit Facility [Line Items]
Line of credit facility, maximum borrowing capacity	$ 4,000,000
Line of credit facility, amortization period	48 months
Line of credit facility, mature date	Aug. 01, 2022
Line of credit facility, beginning date	Sep. 01, 2018
Line of Credit | Silicon Valley Bank
Line Of Credit Facility [Line Items]
Unamortized debt issuance costs			$ 100,000
Credit facility, weighted average interest rate			6.30%
Line of Credit | Term Loan Prepaid On or Before August 17, 2019
Line Of Credit Facility [Line Items]
Percentage of prepayment fee	2.00%
Line of Credit | Term Loan Prepaid After August 17, 2019, but on or before August 17, 2020
Line Of Credit Facility [Line Items]
Percentage of prepayment fee	1.00%
Revolving Credit Facility
Line Of Credit Facility [Line Items]
Line of credit facility, maximum borrowing capacity		$ 25,000,000
Revolving Credit Facility | Minimum | LIBOR Rate
Line Of Credit Facility [Line Items]
Line of credit facility, basis rate	2.75%
Revolving Credit Facility | Minimum | Prime Rate
Line Of Credit Facility [Line Items]
Line of credit facility, basis rate	0.00%
Revolving Credit Facility | Maximum | LIBOR Rate
Line Of Credit Facility [Line Items]
Line of credit facility, basis rate	4.00%
Revolving Credit Facility | Maximum | Prime Rate
Line Of Credit Facility [Line Items]
Line of credit facility, basis rate	1.25%
Letter of Credit
Line Of Credit Facility [Line Items]
Line of credit facility, maximum borrowing capacity		5,000,000
Term Loan
Line Of Credit Facility [Line Items]
Term loan incurred		$ 9,000,000
Term Loan | Line of Credit | Silicon Valley Bank
Line Of Credit Facility [Line Items]
Term loan and equipment advance outstanding amount			$ 20,000,000
Equipment Term Loan Facility | Line of Credit | Silicon Valley Bank
Line Of Credit Facility [Line Items]
Term loan and equipment advance outstanding amount			$ 3,700,000