Amortization of debt discount and accrual of final payment.

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Debt covenant percentage requirement of cash and cash equivalents.

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Additional debt instrument interest rate percentage in the event of default.

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Debt Instrument Covenant Minimum Cash And Cash Equivalents

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Final payment fee.

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Final payment fee as a percentage of aggregate principal amount of borrowings.

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Number of tranches.

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Exercise price per share or per unit of warrants or rights outstanding.

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Number of securities into which the class of warrant or right may be converted. For example, but not limited to, 500,000 warrants may be converted into 1,000,000 shares.

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The number of warrants issued in exchange for the original debt being converted in a noncash (or part noncash) transaction. "Part noncash" refers to that portion of the transaction not resulting in cash receipts or cash payments in the period.

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- Definition

Percentage points added to the reference rate to compute the variable rate on the debt instrument.

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No definition available.

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- Definition

Amount, before unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt.

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- Definition

Effective interest rate for the funds borrowed under the debt agreement considering interest compounding and original issue discount or premium.

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Contractual interest rate for funds borrowed, under the debt agreement.

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Amount, after accumulated amortization, of debt discount.

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Amount of the cost of borrowed funds accounted for as interest expense.

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- Definition

Description of the terms of a credit facility arrangement. Terms typically include interest rate, collateral required, guarantees required, repayment requirements, and restrictions on use of assets and activities of the entity.

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Description of the frequency of periodic payments, which may be presented in a variety of ways (for example, monthly, quarterly, annually).

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Description of the interest rate for the amounts borrowed under the credit facility, including the terms and the method for determining the interest rate (for example, fixed or variable, LIBOR plus a percentage, increasing rate, timing of interest rate resets, remarketing provisions).

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Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

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Expiration date of outstanding warrant and right embodying unconditional obligation requiring redemption by transferring asset at specified or determinable date or upon event certain to occur, in CCYY-MM-DD format.

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Term Loan - Additional Information (Detail)		3 Months Ended
Term Loan - Additional Information (Detail)	Aug. 21, 2018 USD ($) Tranches	Mar. 31, 2019 USD ($) $ / shares shares	Mar. 31, 2018 USD ($)
Debt Instrument [Line Items]
Amount borrowed		$ 5,000,000
Silicon Valley Bank [Member] \| Maximum [Member]
Debt Instrument [Line Items]
Number of common stock issuable \| shares		220,588
Silicon Valley Bank [Member] \| Term Loans [Member]
Debt Instrument [Line Items]
Aggregate principal amount of loans	$ 15,000,000
Number of tranches \| Tranches	3
Loan agreement, description		Contemporaneously with executing the Loan Agreement, the Company drew down the first $5.0 million tranche. The second and third $5.0 million tranches may be drawn only upon the achievement of certain development milestones.
Loan agreement, frequency of payments		Monthly
Interest payment description		Borrowings under the Loan Agreement bear interest at the greater of (i) 6.0% or (ii) a floating per annum rate 1.0% above the prime rate (for an interest rate of 6.50% at March 31, 2019), with interest only due and payable monthly, until March 1, 2020, at which time interest and principal will be due and payable monthly in equal monthly payments; are subject to a final payment fee equal to 6.75% of the aggregate principal amount.
Final payment fee as percent of aggregate principal amount of borrowing	6.75%
Minimum requirement of cash and cash equivalents held with bank		$ 10,000,000
Minimum percentage requirement of cash and cash equivalents held with bank		80.00%
Applicable interest rate of loan		5.00%
Loan payment fee		$ 300,000
Interest expense		$ 100,000	$ 0
Silicon Valley Bank [Member] \| Term Loans [Member] \| Prime Rate [Member]
Debt Instrument [Line Items]
Loan agreement bear interest rate		6.50%
Variable rate on borrowings above prime rate, percentage	1.00%
Silicon Valley Bank [Member] \| Term Loans [Member] \| Minimum [Member]
Debt Instrument [Line Items]
Loan agreement bear interest rate	6.00%
Silicon Valley Bank [Member] \| Term Loans [Member] \| Tranche One [Member]
Debt Instrument [Line Items]
Aggregate principal amount of loans	$ 5,000,000
Amount borrowed	5,000,000
Effective interest rate of loan		9.89%
Unamortized debt discount		$ 100,000
Amortization of debt discount and accrual of final payment		$ 100,000
Silicon Valley Bank [Member] \| Term Loans [Member] \| Tranche Two [Member]
Debt Instrument [Line Items]
Aggregate principal amount of loans	5,000,000
Silicon Valley Bank [Member] \| Term Loans [Member] \| Tranche Three [Member]
Debt Instrument [Line Items]
Aggregate principal amount of loans	$ 5,000,000
Silicon Valley Bank [Member] \| Warrants to Purchase Common Stock [Member]
Debt Instrument [Line Items]
Warrant expiration date		Aug. 21, 2028
Silicon Valley Bank [Member] \| Warrants to Purchase Common Stock [Member] \| Term Loans [Member]
Debt Instrument [Line Items]
Warrants issued in connection with loan \| shares		73,529
Price per share of issued warrants \| $ / shares		$ 1.87