Significant Accounting Policies - Schedule of Potential Shares Outstanding Excluded in Computation of Diluted Net Loss Per Common Share (Detail) - shares	9 Months Ended
Sep. 30, 2019	Sep. 30, 2018
Shares issuable upon exercise of stock options [Member]
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Securities that could potentially dilute basic earnings per share	1,986,201	1,507,268
Non-vested shares under restricted stock grants [Member]
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Securities that could potentially dilute basic earnings per share	848,859	848,859

Securities (including those issuable pursuant to contingent stock agreements) that could potentially dilute basic earnings per share (EPS) or earnings per unit (EPU) in the future that were not included in the computation of diluted EPS or EPU because to do so would increase EPS or EPU amounts or decrease loss per share or unit amounts for the period presented.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=6371337&loc=d3e3550-109257

Name:	us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration