v3.19.1
Notes Payable - Schedule of Notes Payable (Detail) - USD ($)
Mar. 31, 2019
Dec. 31, 2018
Nov. 30, 2018
Oct. 31, 2018
Jan. 31, 2018
Debt Instrument [Line Items]          
Total face amount $ 8,833,000 $ 9,117,000      
Unamortized discount (1,259,000) (1,780,000)     $ (271,000)
Total carrying value 7,574,000 7,337,000      
Amount classified as current 4,726,000 4,464,000      
Amount classified as long-term 2,848,000 2,873,000      
8% Secured Promissory Notes Due August 2018 [Member]          
Debt Instrument [Line Items]          
Total face amount   250,000      
0% Convertible Notes Due January 2021 [Member]          
Debt Instrument [Line Items]          
Total face amount 275,000 275,000      
4% Promissory Note Due April 2021 [Member]          
Debt Instrument [Line Items]          
Total face amount 813,000 847,000      
0% Promissory Note Due April 2019 [Member]          
Debt Instrument [Line Items]          
Total face amount 418,000 418,000      
8% Promissory Note Due March 2021 [Member]          
Debt Instrument [Line Items]          
Total face amount 2,107,000 2,107,000      
12% Convertible Notes Due October 2019 [Member]          
Debt Instrument [Line Items]          
Total face amount 4,000,000 4,000,000      
Unamortized discount       $ (1,942,000)  
12% Convertible Notes Due November 2019 [Member]          
Debt Instrument [Line Items]          
Total face amount $ 1,220,000 $ 1,220,000      
Unamortized discount     $ (118,000)