Quarterly report pursuant to Section 13 or 15(d)

Stock-Based Compensation (Restricted Stock) (Details)

v3.19.1
Stock-Based Compensation (Restricted Stock) (Details)
$ / shares in Units, $ in Thousands
3 Months Ended
Mar. 31, 2019
USD ($)
$ / shares
shares
Unvested restricted stock units and awards  
Number of Shares  
Balance at the beginning of the period (in shares) 1,585,788
Granted (in shares) 940,614
Vested (in shares) (479,479)
Forfeited (in shares) (24,866)
Balance at the end of the period (in shares) 2,022,057
Weighted-Average Grant Date Fair Value per Share  
Balance at the beginning of the period (in dollars per share) | $ / shares $ 46.33
Granted (in dollars per share) | $ / shares 61.18
Vested (in dollars per share) | $ / shares 45.98
Forfeited (in dollars per share) | $ / shares 51.27
Balance at the end of the period (in dollars per share) | $ / shares $ 53.26
Share-based Compensation Arrangement by Share-based Payment Award, Additional General Disclosures [Abstract]  
Unrecognized compensation expense related to shares | $ $ 99,802
Unrecognized compensation expense weighted-average recognition period 2 years 4 months 24 days
Performance Shares  
Number of Shares  
Granted (in shares) 69,000
Share-based Compensation Arrangement by Share-based Payment Award, Additional General Disclosures [Abstract]  
Vesting period 3 years
Performance Shares | Minimum  
Share-based Compensation Arrangement by Share-based Payment Award, Additional General Disclosures [Abstract]  
Number of shares to be vest upon each evaluation date, percentage 50.00%
Performance Shares | Maximum  
Share-based Compensation Arrangement by Share-based Payment Award, Additional General Disclosures [Abstract]  
Number of shares to be vest upon each evaluation date, percentage 150.00%