Quarterly report pursuant to Section 13 or 15(d)

Stock-Based Compensation (ResSt) (Details)

v3.8.0.1
Stock-Based Compensation (ResSt) (Details)
$ / shares in Units, $ in Thousands
 3 Months Ended 9 Months Ended
Sep. 30, 2017
USD ($)
$ / shares
shares
Jun. 30, 2017
$ / shares
shares
Mar. 31, 2017
$ / shares
shares
Sep. 30, 2017
USD ($)
$ / shares
shares
Dec. 31, 2015
tranche
Restricted Stock Units          
Stock-Based compensation          
Award vesting rights proportion (as a percent)       0.33%  
Number of annual vesting rights tranches | tranche         3
Unvested restricted stock units and awards          
Number of Shares          
Balance at the beginning of the period (in shares) | shares 2,023,898 2,221,044 1,894,759 1,894,759  
Granted (in shares) | shares 29,000 47,700 872,941    
Vested (in shares) | shares (121,449) (199,163) (526,572)    
Forfeited (in shares) | shares (30,369) (45,683) (20,084)    
Balance at the end of the period (in shares) | shares 1,901,080 2,023,898 2,221,044 1,901,080  
Weighted-Average Grant Date Fair Value per Share          
Balance at the beginning of the period (in dollars per share) | $ / shares $ 32.17 $ 31.98 $ 30.40 $ 30.40  
Granted (in dollars per share) | $ / shares 39.10 35.05 31.89    
Vested (in dollars per share) | $ / shares 32.26 30.59 31.68    
Forfeited (in dollars per share) | $ / shares 31.61 30.11 27.52    
Balance at the end of the period (in dollars per share) | $ / shares $ 32.28 $ 32.17 $ 31.98 $ 32.28  
Additional disclosures          
Unrecognized compensation expense related to shares | $ $ 49,527     $ 49,527  
Unrecognized compensation expense weighted-average recognition period       2 years  
Stock options          
Additional disclosures          
Unrecognized compensation expense weighted-average recognition period       1 year 9 months 18 days