Long-term Debt - Additional Information (Detail)			12 Months Ended
		Dec. 28, 2017 USD ($) Tranche	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)
Debt Instrument [Line Items]
Line of credit facility, advance amount			$ 20,000,000
Line of credit facility, interest rate		8.05%
Line of credit facility, interest rate description			Advances under the Credit Facility bear an interest rate equal to the greater of either (i) 8.05% plus the prime rate as reported from time to time in The Wall Street Journal minus 4.75%, and (ii) 8.05%. At December 31, 2019, the interest rate on the outstanding borrowings under the Credit Facility was 8.05%. For advances made under the first and second tranches, the Company will make interest-only payments through July 1, 2021, and will then repay the principal balance and interest on the advances in equal monthly installments after the interest-only period and continuing through December 1, 2022.
Proceeds from issuance of common stock			$ 73,276,000	$ 0	$ 0
Borrowings outstanding			19,786,000
Discount on borrowings			$ 214,000
Term Loan [Member]
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity		$ 50,000,000
Number of tranches | Tranche		3
Line of credit facility, interest rate			8.05%
Line of credit facility, maturity date			Dec. 01, 2022
Line of credit facility, prepayment description		The Company may prepay advances under the Credit Facility, in whole or in part, at any time, subject to a prepayment charge equal to: (a) 1.5% of the amount so prepaid, if such prepayment occurs during the second year following the Closing Date; and (b) 1.0% of the amount so prepaid, if such prepayment occurs after the second year following the Closing Date. The Credit Facility is secured by substantially all of the Company’s assets, excluding intellectual property.
Loan commitment charge, percentage		1.00%
Borrowings outstanding	[1]		$ 19,786,000	19,689,000
Discount on borrowings			$ 214,000	$ 311,000
Term Loan [Member] | Tranche One [Member]
Debt Instrument [Line Items]
End of term charge amount for loan		$ 900,000
Term Loan [Member] | Tranche Two [Member]
Debt Instrument [Line Items]
End of term charge amount for loan		300,000
Term Loan [Member] | Minimum [Member]
Debt Instrument [Line Items]
Aggregate proceeds to be received from equity offering		20,000,000
Loan commitment charge		162,500
Term Loan [Member] | Hercules Capital Inc [Member] | Maximum [Member]
Debt Instrument [Line Items]
Proceeds from issuance of common stock		$ 2,000,000
Term Loan [Member] | Second Year [Member]
Debt Instrument [Line Items]
Line of credit facility, prepayment interest rate		1.50%
Term Loan [Member] | After Second Year [Member]
Debt Instrument [Line Items]
Line of credit facility, prepayment interest rate		1.00%
Term Loan [Member] | Wall Street Journal Prime [Member]
Debt Instrument [Line Items]
Line of credit facility, interest rate			4.75%

[1] Carrying amounts of long-term debt were net of unamortized debt discounts of $214,000 and $311,000 as of December 31, 2019 and 2018, respectively.