Stockholders' Equity - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands			1 Months Ended						12 Months Ended
	Mar. 12, 2019	Nov. 03, 2017	Sep. 20, 2018	Nov. 30, 2017	May 31, 2017	May 21, 2017	Jun. 30, 2016	Jun. 30, 2015	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Shareholders Equity [Line Items]
Common Stock, shares issued									680	567
Stock Issued During Period, Shares, New Issues							29,412
Stock Issued During Period, Value, New Issues									$ 1,180	$ 3,567
Stockholders' Equity Attributable to Parent									1,218	8,067	$ 8,240
Proceeds from Issuance of Common Stock	$ 17,000								$ 1,180	$ 3,567
Class Of Warrant Or Right Exercisable Number					22,059	22,059
Class Of Warrant Or Right Exercised Number					559	559
New Warrants [Member]
Shareholders Equity [Line Items]
Class of Warrant or Right, Exercise Price of Warrants or Rights					$ 120.00	$ 120.00
Proceeds from Issuance of Common Stock					$ 1,500
Proceeds from Warrant Exercises						$ 1,500
Reduced Exercise Price [Member]
Shareholders Equity [Line Items]
Class of Warrant or Right, Exercise Price of Warrants or Rights					$ 76.00	$ 76.00
Class Of Warrant Or Right Exercised Number					21,500	21,500
Registered Direct Offering 2017 [Member]
Shareholders Equity [Line Items]
Stock Issued During Period, Shares, New Issues		66,667		66,667
Stock Issued During Period, Value, New Issues		$ 4,000		$ 4,000
Proceeds from Issuance of Common Stock				$ 3,600
2018 Registered Direct Offering
Shareholders Equity [Line Items]
Stock Issued During Period, Shares, New Issues			98,454
Stock Issued During Period, Value, New Issues			$ 1,500
Warrant
Shareholders Equity [Line Items]
Stock Issued During Period, Shares, New Issues							14,706
Class of Warrant or Right, Number of Securities Called by Warrants or Rights						12,500
Stock Issued During Period, Value, New Issues							$ 10,000	$ 25,000
Proceeds from Issuance of Common Stock			$ 1,200
Warrant | Registered Direct Offering 2017 [Member]
Shareholders Equity [Line Items]
Stock Issued During Period, Shares, New Issues		33,334		33,334
Warrant | 2018 Registered Direct Offering
Shareholders Equity [Line Items]
Stock Issued During Period, Shares, New Issues			14,624
Series A Warrants [Member] | Private Placement [Member]
Shareholders Equity [Line Items]
Stock Issued During Period, Shares, New Issues			113,077
Roth Capital Partners, Llc [Member] | Warrant | Registered Direct Offering 2017 [Member]
Shareholders Equity [Line Items]
Stock Issued During Period, Shares, New Issues		800		800
HC Wainwright Co [Member] | 2018 Registered Direct Offering
Shareholders Equity [Line Items]
Stock Issued During Period, Shares, New Issues			6,785