Organization and Business - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands			1 Months Ended				3 Months Ended
	Mar. 12, 2019	Jan. 14, 2019	Jan. 18, 2019	Jan. 17, 2019	Sep. 20, 2018	Jun. 30, 2015	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Organization and Nature of Operations [Line Items]
Stock issued during period, shares, new issues			648,233
Stock issued during period, value, new issues			$ 1,700				$ 19,411
Proceeds from Issuance of Common Stock	$ 17,000	$ 900	$ 1,500				$ 19,411	$ 0
Class of Warrant or Right, Number of Securities Called by Warrants or Rights			324,117
Stockholders' Equity, Reverse Stock Split			1-for-20	common stock at a ratio of 1-for-20, and our common stock began trading on the split-adjusted basis on the Nasdaq Capital Market at the commencement of trading on January 18, 2019. All common stock share and per share amounts in our consolidated financial statements have been adjusted to give effect to the 1-for-20 reverse stock split.
Common Stock, Shares, Issued							2,814,000		680,000
Warrants 2016 [Member]
Organization and Nature of Operations [Line Items]
Proceeds from Issuance of Common Stock					$ 1,200
Warrant
Organization and Nature of Operations [Line Items]
Stock issued during period, value, new issues						$ 25,000
Warrants issued	42,775
HC Wainwright LLC [Member]
Organization and Nature of Operations [Line Items]
Shares Issued, Price Per Share		$ 2.418
Common Stock [Member]
Organization and Nature of Operations [Line Items]
Stock issued during period, shares, new issues			38,894				1,794,000
Stock issued during period, value, new issues							$ 2
2018 Registered Direct Offering
Organization and Nature of Operations [Line Items]
Stock issued during period, shares, new issues					98,454
Stock issued during period, value, new issues					$ 1,500
2018 Registered Direct Offering | Warrant
Organization and Nature of Operations [Line Items]
Stock issued during period, shares, new issues					14,624
Private Placement [Member]
Organization and Nature of Operations [Line Items]
Common Stock, Shares, Issued		25,777
Private Placement [Member] | Series A Warrants [Member]
Organization and Nature of Operations [Line Items]
Stock issued during period, shares, new issues					113,077
IPO [Member]
Organization and Nature of Operations [Line Items]
Stock issued during period, shares, new issues	712,910	429,616
Stock issued during period, value, new issues	$ 18,500
Proceeds from Issuance of Common Stock		$ 1,100
Shares Issued, Price Per Share		$ 2.60
HC Wainwright Co [Member] | 2018 Registered Direct Offering
Organization and Nature of Operations [Line Items]
Stock issued during period, shares, new issues					6,785