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Stockholders' Equity and Stock-Based Compensation - Summary of Market-based Restricted Stock Vesting Activity (Detail) - USD ($)
$ in Thousands
12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]      
Compensation Cost Recognized Upon Vesting (in millions) $ 38,513 $ 22,546 $ 3,010
Market-based Restricted Stock [Member] | Market-based Vesting Conditions [Member] | Vest Date May 13, 2017 [Member]      
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]      
Date Vested May 13, 2017    
Number of Shares Vested 229,075    
Compensation Cost Recognized Upon Vesting (in millions) $ 2,900    
Shares withheld to satisfy tax withholding obligations 91,274    
Market-based Restricted Stock [Member] | Market-based Vesting Conditions [Member] | Vest Date June 20, 2017 [Member]      
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]      
Date Vested Jun. 20, 2017    
Number of Shares Vested 248,250    
Compensation Cost Recognized Upon Vesting (in millions) $ 5,200    
Shares withheld to satisfy tax withholding obligations 103,907    
Market-based Restricted Stock [Member] | Market-based Vesting Conditions [Member] | Vest Date August 25, 2017 [Member]      
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]      
Date Vested Aug. 25, 2017    
Number of Shares Vested 153,764    
Compensation Cost Recognized Upon Vesting (in millions) $ 5,500    
Shares withheld to satisfy tax withholding obligations 65,309    
Market-based Restricted Stock [Member] | Market-based Vesting Conditions [Member] | Vest Date September 7, 2017 [Member]      
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]      
Date Vested Sep. 07, 2017    
Number of Shares Vested 244,850    
Compensation Cost Recognized Upon Vesting (in millions) $ 4,200    
Shares withheld to satisfy tax withholding obligations 102,548    
Market-based Restricted Stock [Member] | Market-based Vesting Conditions [Member] | Vest Date October 13, 2017 [Member]      
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]      
Date Vested Oct. 13, 2017    
Number of Shares Vested 138,490    
Compensation Cost Recognized Upon Vesting (in millions) $ 4,300    
Shares withheld to satisfy tax withholding obligations 57,916