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Stock-based Compensation - Additional Information (Details) - USD ($)
$ / shares in Units, $ in Thousands
1 Months Ended 6 Months Ended
Jan. 31, 2017
Jun. 30, 2019
Jun. 30, 2018
Dec. 31, 2018
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]        
Cash proceeds received upon the exercise of options   $ 2,168 $ 10,147  
Fair value of SAR liability   572   $ 1,639
Unrecognized compensation cost   $ 23,099    
Weighted-average period of unrecognized compensation cost expected to be recognized   2 years 9 months 14 days    
Stock Options        
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]        
Weighted average grant date fair value per share of options   $ 2.45 $ 8.76  
Cash proceeds received upon the exercise of options   $ 2,168 $ 10,147  
Intrinsic value of stock options exercised   $ 6,087 $ 83,861  
Stock Appreciation Rights        
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]        
Number of shares granted 110,000      
Grant-date price per share $ 12.24      
Grant-date fair value per share $ 4.52      
Award vesting period 4 years      
Award expiration period 10 years      
Number of award outstanding   240,000    
Number of award unvested   19,000    
Number of award exercisable   221,000    
Fair value of SAR   $ 2.42    
Stock Appreciation Rights | Accrued Expenses And Other Current Liabilities        
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]        
Fair value of SAR liability   $ 521   $ 1,387
2017 Stock Incentive Plan        
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]        
Number of shares authorized for grant   13,500,000    
Number of remaining shares available for grant   10,739,000    
2011 and 2017 Stock Incentive Plan | Restricted Stock Units        
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]        
Number of shares granted   1,117,000    
Grant-date fair value per share   $ 10.90    
Number of award outstanding   1,549,000   759,000
2011 and 2017 Stock Incentive Plan | Restricted Stock Units | Common Stock        
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]        
Shares of common stock in settlement of employee tax withholding obligations   76,000 0