Net Income (Loss) Per Common Share - Schedule of Potential Dilutive Common Shares (Parenthetical) (Detail) - Series B Redeemable Convertible Preferred Stock [Member] - $ / shares	Dec. 31, 2017	Dec. 07, 2017
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Conversion ceiling price of common stock	$ 2.25	$ 2.25
Preferred stock conversion price per share	$ 1.35

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.

No definition available.

Name:	us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration