Debt and Fair Value of Financial Instruments - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Millions	May 03, 2018	Mar. 06, 2018	Jan. 30, 2018	Jan. 29, 2018	Sep. 30, 2018
Secured Promissory Note [Member] | Steven L. and Monique P. Elfman [Member]
Debt And Fair Value Of Financial Instruments [Line Items]
Notes due date			Feb. 11, 2018	Aug. 18, 2017
Secured Promissory Note [Member] | William W. Smith, Jr. and Dieva L. Smith [Member]
Debt And Fair Value Of Financial Instruments [Line Items]
Notes due date			Jul. 25, 2018	Jun. 26, 2017
Debt instrument extended maturity date		Mar. 25, 2020
Secured Promissory Note [Member] | Next Generation TC FBO Andrew Arno IRA 1663 [Member]
Debt And Fair Value Of Financial Instruments [Line Items]
Notes due date			Jul. 25, 2018	Aug. 24, 2017
Debt instrument extended maturity date		Mar. 25, 2020
Secured Promissory Note [Member] | Andrew Arno [Member]
Debt And Fair Value Of Financial Instruments [Line Items]
Notes due date			Jul. 25, 2018	Aug. 24, 2017
Debt instrument extended maturity date		Mar. 25, 2020
March Offering [Member]
Debt And Fair Value Of Financial Instruments [Line Items]
Gross proceeds before deducting placement agent fee and offering expenses		$ 5.0
Warrant liability		$ 2.9			$ 4.7
March Offering [Member] | Common Stock [Member]
Debt And Fair Value Of Financial Instruments [Line Items]
Common shares issued in stock offering, net offering costs, shares		2,857,144
Common stock, price per share		$ 1.75
Common stock exercise price		$ 2.17
May Offering [Member]
Debt And Fair Value Of Financial Instruments [Line Items]
Gross proceeds before deducting placement agent fee and offering expenses	$ 7.0
Warrant liability	$ 3.9				$ 5.2
May Offering [Member] | Common Stock [Member]
Debt And Fair Value Of Financial Instruments [Line Items]
Common shares issued in stock offering, net offering costs, shares	3,170,000
Common stock, price per share	$ 2.21
Common stock exercise price	$ 2.11