Term Loan Agreement (CRG) - Additional Information (Detail)	Dec. 26, 2017 USD ($) $ / shares shares	Feb. 21, 2017 USD ($) Warrant $ / shares shares
Debt Instrument [Line Items]
Remainder of borrowings		$ 13,700,000
CRG [Member] \| Line of Credit [Member]
Debt Instrument [Line Items]
Borrowings outstanding		45,000,000
Additional borrowing capacity upon milestone achievement		30,000,000
Second draw borrowing capacity upon milestone achievement		$ 5,000,000
Loan agreement term		6 years
Loan agreement interest only term		3 years
Loan agreement interest only term threshold		4 years
Agreement maturity date		Dec. 31, 2022
Interest on borrowings		12.50%
Interest on borrowings, interest only period percentage		3.50%
Effective interest on borrowings		9.00%
Final payment fee rate		9.00%
Prepayment period of outstanding principal and accrued unpaid interest		5 years
Prepayment fee after		$ 0
Additional interest rate		4.00%
Number of warrants \| Warrant		5
Warrants issued to purchase shares of common stock \| shares	349,452	1,701,583
Warrants exercise price \| $ / shares	$ 3.42	$ 2.38
CRG [Member] \| Tranche One [Member] \| Line of Credit [Member]
Debt Instrument [Line Items]
Additional borrowing capacity upon milestone achievement		$ 15,000,000
CRG [Member] \| Tranche Two [Member] \| Line of Credit [Member]
Debt Instrument [Line Items]
Additional borrowing capacity upon milestone achievement		$ 15,000,000
Second draw gross proceeds	$ 15,000,000

Debt instrument interest only payment term.

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Debt instrument interest only payment term threshold.

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Debt instrument interest rate stated interest only period percentage.

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Debt instrument prepayment fee after year five.

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Final payment fees percentage.

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- Definition

Line of credit facility additional borrowing capacity upon contingent milestone achievement.

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- Definition

Line of credit facility second draw borrowing capacity upon contingent milestone achievement.

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Number of warrants.

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Prepayment period of outstanding principal and accrued unpaid interest.

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Remaining line of credit after deducting loan origination cost broker and other fees.

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- Definition

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

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(i)(4))
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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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-Name Accounting Standards Codification
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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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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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- Definition

Period of time between issuance and maturity of debt instrument, in PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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- Definition

The carrying value as of the balance sheet date of the current and noncurrent portions of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the agreement.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(22))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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-Publisher FASB
-Name Accounting Standards Codification
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- Definition

Date the credit facility terminates, in CCYY-MM-DD format.

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Amount of cash inflow from contractual arrangement with the lender, including but not limited to, letter of credit, standby letter of credit and revolving credit arrangements.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
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-Section 45
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