Quarterly report pursuant to Section 13 or 15(d)

Stockholders' Equity - Additional Information (Detail)

v3.19.1
Stockholders' Equity - Additional Information (Detail)
$ in Thousands, shares in Millions
 1 Months Ended 3 Months Ended 12 Months Ended
Jan. 31, 2018
USD ($)
shares
Mar. 31, 2019
USD ($)
Mar. 31, 2018
USD ($)
shares
Dec. 31, 2018
USD ($)
Class of Stock [Line Items]        
Detailed engineering costs recognized       $ 50,000
Conversion ratio   1    
Fees and commissions   $ 0 $ 526  
Over-allotment Option        
Class of Stock [Line Items]        
Aggregate purchase price, net of offering costs $ 14,500      
Option to purchase additional shares of common stock (in shares) | shares 1.5      
Fees and commissions $ 500      
Convertible Preferred Stock        
Class of Stock [Line Items]        
Convertible preferred stock, shares issued (in shares) | shares     6.1  
Discharged amounts outstanding     $ 22,700  
Amounts to be invoiced     $ 27,300  
Maximum | At-the-Market Program        
Class of Stock [Line Items]        
Aggregate purchase price, net of offering costs   $ 189,700