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Stockholders' Equity - Additional Information (Detail) - USD ($)
$ / shares in Units, $ in Thousands
 12 Months Ended
Jul. 16, 1999
Dec. 31, 2020
Dec. 31, 2019
Dec. 31, 2018
Mar. 16, 2020
May 01, 2018
Class of Stock [Line Items]            
Liquidation value of outstanding preferred stock   $ 3,649        
Preferred stock voting right   Series AA preferred stock is entitled to one vote per share.        
Class B common stock voting rights   holders of Class B common stock have ten votes per share on all matters in which the holders of common stock are entitled to vote and holders of Class A common stock have one vote per share on such matters.        
Shares issued     266,410 576,002    
Shelf Registration [Member]            
Class of Stock [Line Items]            
Shares issued   0 0      
Series AA Preferred Stock [Member]            
Class of Stock [Line Items]            
Preferred stock, shares authorized 5,720 5,720 5,720      
Preferred stock, par value $ 0.001 $ 0.001 $ 0.001      
Dividends paid to preferred stock 15.95          
Amount entitled $ 638          
Preferred Class A [Member]            
Class of Stock [Line Items]            
Preferred stock, shares authorized 1,000,000          
Common Class A [Member]            
Class of Stock [Line Items]            
Common stock, par value   $ 0.001 $ 0.001     $ 0.001
Issuance of shares related to acquisition       163,137    
Common Class A [Member] | Stock Repurchase Program [Member]            
Class of Stock [Line Items]            
Stock repurchase program, authorized amount         $ 250,000  
Stock repurchase program expiry date   Sep. 30, 2021        
Stock repurchased during period   $ 0        
Common Class A [Member] | Equity Distribution Agreement [Member]            
Class of Stock [Line Items]            
Common stock, shares sold   842,412        
Common stock, shares available to be sold   $ 336,668        
Common Class A [Member] | Maximum [Member]            
Class of Stock [Line Items]            
Aggregate offering price of common stock issuable           $ 400,000