Quarterly report pursuant to Section 13 or 15(d)

Warrants - Additional Information (Details)

v3.19.1
Warrants - Additional Information (Details) - USD ($)
3 Months Ended
Jun. 08, 2018
May 31, 2018
May 02, 2018
Apr. 26, 2018
Mar. 31, 2019
Mar. 31, 2018
Class Of Warrant Or Right [Line Items]            
Stock issued during period, value, new issues         $ 6,596,000 $ 1,793,000
Class of warrant or right, exercise price of warrants or rights         $ 0.01  
Carlyle Group | Convertible Senior Notes Converted to Warrants            
Class Of Warrant Or Right [Line Items]            
Class of warrant or right, exercise price of warrants or rights     $ 0.01      
Debt conversion, original debt, amount     $ 50,000,000      
Warrants Issued in Private Placement            
Class Of Warrant Or Right [Line Items]            
Class of warrant or right, outstanding       2,168,586    
Class of warrant or right, number of securities called by warrants or rights       674,164    
Class of warrant or right, exercise price of warrants or rights       $ 0.01    
PIPE Warrants            
Class Of Warrant Or Right [Line Items]            
Class of warrant or right, exercise price of warrants or rights       $ 0.01    
Warrants and rights outstanding, term       25 years    
Exchange Warrants            
Class Of Warrant Or Right [Line Items]            
Class of warrant or right, outstanding         2,271,406  
Class of warrant or right, exercise price of warrants or rights     $ 0.01      
Warrants and rights outstanding, term     25 years      
Class of warrant or right, exercised during period 38,857 250,693        
Class of warrant or right, exercised during period, exercise price $ 0.01 $ 0.01        
Exchange Warrants | Carlyle Group            
Class Of Warrant Or Right [Line Items]            
Class of warrant or right, number of securities called by warrants or rights     1,886,292      
Private Placement            
Class Of Warrant Or Right [Line Items]            
Stock issued during period, value, new issues       $ 56,855,000