Quarterly report pursuant to Section 13 or 15(d)

Stock-Based Compensation (Narrative) (Details)

v3.19.1
Stock-Based Compensation (Narrative) (Details) - USD ($)
$ / shares in Units, shares in Thousands, $ in Thousands
3 Months Ended
Mar. 31, 2019
Mar. 31, 2018
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]    
Stock-based compensation expense $ 5,631 $ 5,236
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Dividend rate used 0.00%  
Options    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Unrecognized compensation cost related to unvested options $ 7,000  
Weighted average period for compensation cost to be recognized 1 year 2 months 12 days  
RSAs    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Unrecognized compensation cost related to unvested restricted shares $ 27,000  
Weighted average period for compensation cost to be recognized 2 years 4 days  
Series B common stock    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Shares reserved for issuance upon exercise 1,200  
Series A common stock    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Shares reserved for issuance upon exercise 1,600  
CEO | Series B common stock | Performance-based RSUs    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Number of shares granted 51  
Granted shares, weighted average GDFV (in dollars per share) $ 53.78  
Award vesting period 1 year