Quarterly report pursuant to Section 13 or 15(d)

Stockholders' Equity - Additional Information (Detail)

v3.19.2
Stockholders' Equity - Additional Information (Detail)
$ / shares in Units, $ in Thousands
 1 Months Ended 6 Months Ended
May 23, 2019
USD ($)
$ / shares
shares
Jun. 30, 2018
USD ($)
shares
Jan. 31, 2018
USD ($)
shares
Jun. 30, 2019
USD ($)
Jun. 30, 2018
USD ($)
Dec. 31, 2018
USD ($)
Mar. 31, 2018
USD ($)
shares
Class of Stock [Line Items]              
Aggregate purchase price, net of offering costs   $ 115,200          
Number of shares for purchase under warrant (in shares) | shares 1,500,000            
Fair value of warrant $ 3,300            
Common stock purchase price (in dollars per share) | $ / shares $ 10.00            
Warrant term (in years) 5 years            
Deferred engineering costs       $ 86,591   $ 69,000  
Conversion ratio       1      
Option to purchase additional shares of common stock (in shares) | shares   12,000,000.0          
Fees and commissions   $ 3,600   $ 0 $ 4,090    
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   1,800,000 1,500,000        
Fees and commissions     $ 500        
Convertible Preferred Stock              
Class of Stock [Line Items]              
Convertible preferred stock, shares issued (in shares) | shares             6,100,000
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      
Driftwood Project              
Class of Stock [Line Items]              
Deferred engineering costs           $ 50,000