Summary of Outstanding Warrants Issued by Company (Detail) - $ / shares			6 Months Ended
	Feb. 08, 2017	Aug. 13, 2014	Jun. 30, 2017
Class Of Warrant Or Right [Line Items]
Number of Shares Issuable Upon Exercise			951,878
2014 Consultant Warrant
Class Of Warrant Or Right [Line Items]
Number of Shares Issuable Upon Exercise			85,000
Weighted Average Exercise Price		$ 10.70	$ 10.70
Issue Date			Aug. 13, 2014
Expiration Date		Aug. 13, 2019	Aug. 13, 2019
East West Bank Warrant
Class Of Warrant Or Right [Line Items]
Number of Shares Issuable Upon Exercise			40,000
Weighted Average Exercise Price	$ 3.64		$ 3.64
Issue Date			Feb. 08, 2017
Expiration Date	Feb. 08, 2022		Feb. 08, 2022
VLL7 and VLL8 Warrants
Class Of Warrant Or Right [Line Items]
Number of Shares Issuable Upon Exercise			580,000
Weighted Average Exercise Price			$ 2.00
Issue Date			Feb. 08, 2017
Expiration Date			Feb. 08, 2022
2017 Consultant Warrant
Class Of Warrant Or Right [Line Items]
Number of Shares Issuable Upon Exercise			60,000
Weighted Average Exercise Price	$ 4.60		$ 4.60
Issue Date			Feb. 08, 2017
Expiration Date	Feb. 08, 2019		Feb. 08, 2019
2013 Private Placement Warrants
Class Of Warrant Or Right [Line Items]
Number of Shares Issuable Upon Exercise			186,878
Weighted Average Exercise Price			$ 10.00
Issue Date			Aug. 14, 2013
Expiration Date			Aug. 14, 2017