Annual report pursuant to Section 13 and 15(d)

Stockholders' Equity (Deficit) - Schedule of Issuance of Warrants to Purchase Shares of Common Stock (Detail)

v3.8.0.1
Stockholders' Equity (Deficit) - Schedule of Issuance of Warrants to Purchase Shares of Common Stock (Detail) - $ / shares
 12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Class of Warrant or Right [Line Items]    
Number of shares of common stock 1,122,840 2,552,068
10% Warrant [Member]    
Class of Warrant or Right [Line Items]    
Vesting terms 50% on issuance; 50% in May 2018  
Life in years 5 years  
Exercise Price $ 13.6088  
Number of shares of common stock 809,400  
Bridge Loan Warrants [Member]    
Class of Warrant or Right [Line Items]    
Vesting terms Fully vested on issuance  
Life in years 10 years  
Exercise Price $ 13.6088  
Number of shares of common stock 313,440  
Acacia Note Warrants [Member]    
Class of Warrant or Right [Line Items]    
Vesting terms   Fully vested on issuance
Life in years   4 years
Exercise Price   $ 13.6088
Number of shares of common stock   154,311
Acacia Primary Warrants [Member]    
Class of Warrant or Right [Line Items]    
Vesting terms   Fully vested on issuance
Life in years   5 years
Exercise Price   $ 13.6088
Number of shares of common stock   2,150,335
Westwood One [Member]    
Class of Warrant or Right [Line Items]    
Vesting terms   Upon achievement of performance condition
Life in years   10 years
Exercise Price   $ 8.0833
Number of shares of common stock   247,422