Annual report pursuant to Section 13 and 15(d)

Summary of Warrant Activity (Detail)

v3.8.0.1
Summary of Warrant Activity (Detail) - Warrants - $ / shares
shares in Thousands
12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Shares      
Beginning Balance 11,406 10,094 10,094
Granted/Issued 3,926 2,035
Exercised    
Forfeited, cancelled, or expired (9,206) (723)
Ending Balance 6,126 11,406 10,094
Warrants exercisable, December 31, 2017 5,991    
Vested warrants expired during the 12 months ended December 31, 2017 9,206    
Weighted-Average Exercise Price Per Share      
Beginning Balance $ 4.18 $ 4.18 $ 4.18
Granted/Issued 1.80 2.00
Exercised    
Forfeited, cancelled, or expired 4.00 6.50
Ending Balance 1.93 $ 4.18 $ 4.18
Warrants exercisable, December 31, 2017 1.88    
Vested warrants expired during the 12 months ended December 31, 2017 $ 4.00