Notes Payable - Schedule of Notes Payable (Detail) - USD ($)	Sep. 30, 2018	Jan. 31, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Total face amount	$ 6,107,000		$ 8,940,000
Less unamortized discount	(60,000)	$ (271,000)	(26,000)
Total carrying value	6,047,000		8,914,000
Amount classified as current	3,059,000		3,374,000
Amount classified as long-term	2,988,000		5,540,000
Class B Promissory Notes [Member]
Debt Instrument [Line Items]
Total face amount			100,000
Class C Promissory Notes [Member]
Debt Instrument [Line Items]
Total face amount			333,000
10% Promissory Note Due on Demand [Member]
Debt Instrument [Line Items]
Total face amount			500,000
8% Convertible Promissory Note Due March 2019 [Member]
Debt Instrument [Line Items]
Total face amount	250,000		250,000
8% Secured Promissory Notes Due July/August 2018 In Default [Member]
Debt Instrument [Line Items]
Total face amount	600,000		1,350,000
0% Promissory Notes Due January and March 2018 [Member]
Debt Instrument [Line Items]
Total face amount			715,000
0% Promissory Notes Due May 2018 In Default [Member]
Debt Instrument [Line Items]
Total face amount	218,000		261,000
8% Promissory Notes In Default [Member]
Debt Instrument [Line Items]
Total face amount			200,000
8% Promissory Notes Due March 2019 [Member]
Debt Instrument [Line Items]
Total face amount			1,776,000
8% Secured Promissory Notes Due March 2019 [Member]
Debt Instrument [Line Items]
Total face amount			$ 3,455,000
0% Convertible Notes Due January 2021 [Member]
Debt Instrument [Line Items]
Total face amount	275,000
4% Promissory Note Due April 2021 [Member]
Debt Instrument [Line Items]
Total face amount	1,000,000
0% Promissory Note Due November 2018 [Member]
Debt Instrument [Line Items]
Total face amount	789,000
0% Promissory Note Due April 2019 [Member]
Debt Instrument [Line Items]
Total face amount	868,000
8% Promissory Note Due March 2021 [Member]
Debt Instrument [Line Items]
Total face amount	$ 2,107,000