Equity Transactions - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands				3 Months Ended	9 Months Ended
	May 03, 2018	Apr. 19, 2018	Mar. 06, 2018	Mar. 31, 2018	Sep. 30, 2018	Sep. 30, 2017
Class Of Stock [Line Items]
Cash proceeds from issuance of common stock, net of offering costs					$ 10,749	$ 2,056
Preferred stock, dividend rate			10.00%
Preferred stock liquidation damage payments		$ 48
Roth Capital Partners, LLC [Member]
Class Of Stock [Line Items]
Percentage of gross proceeds of offering	2.00%
Warrants [Member]
Class Of Stock [Line Items]
Triggering event charges				$ 11
March Offering [Member]
Class Of Stock [Line Items]
Gross proceeds before deducting placement agent fee and offering expenses			$ 5,000
Cash proceeds from issuance of common stock, net of offering costs			$ 4,500
March Offering [Member] | Common Stock [Member]
Class Of Stock [Line Items]
Common stock, issued and sold to investors			2,857,144
Common stock, price per share			$ 1.75
Common stock exercise price			2.17
May Offering [Member]
Class Of Stock [Line Items]
Gross proceeds before deducting placement agent fee and offering expenses	$ 7,000
Cash proceeds from issuance of common stock, net of offering costs	$ 6,300
May Offering [Member] | Common Stock [Member]
Class Of Stock [Line Items]
Common stock, issued and sold to investors	3,170,000
Common stock, price per share	$ 2.21
Common stock exercise price	$ 2.11
Chardan Capital Markets, LLC [Member]
Class Of Stock [Line Items]
Common stock exercise price			$ 2.365
Percentage of gross proceeds of offering	7.00%		8.00%
Percentage of warrants to purchase shares of common stock on number of shares sold			3.00%
Warrants term			5 years 6 months
Offering [Member] | Unterberg Koller Capital Fund L.P. [Member] | Maximum [Member]
Class Of Stock [Line Items]
Common stock exercise price			$ 2.14
Offering [Member] | Unterberg Koller Capital Fund L.P. [Member] | Minimum [Member]
Class Of Stock [Line Items]
Common stock exercise price			$ 2.07