Annual report pursuant to Section 13 and 15(d)

Stockholders' Equity - Additional Information (Detail)

v3.10.0.1
Stockholders' Equity - Additional Information (Detail) - $ / shares
 12 Months Ended
Dec. 31, 2018
Dec. 31, 2017
Dec. 31, 2016
Class of Stock [Line Items]      
Preferred Stock, shares authorized 10,000,000 10,000,000  
Preferred Stock, par value $ 0.001 $ 0.001  
Class A Common Stock [Member]      
Class of Stock [Line Items]      
Common Stock, shares authorized 500,000,000 500,000,000  
Common Stock, par value $ 0.001 $ 0.001  
Class B Common Stock [Member]      
Class of Stock [Line Items]      
Common Stock, shares authorized 75,000,000 75,000,000  
Common Stock, par value $ 0.001 $ 0.001  
Certain Class B stockholders converted into Class A 561,876 0 1,733,270