Quarterly report pursuant to Section 13 or 15(d)

Employee Benefits and Compensation Plans - Summary of Share Option Awards (Details)

v3.10.0.1
Employee Benefits and Compensation Plans - Summary of Share Option Awards (Details) - USD ($)
$ / shares in Units, $ in Thousands
6 Months Ended 12 Months Ended
Jun. 30, 2018
Dec. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award, Additional General Disclosures [Abstract]    
Options Outstanding, Weighted- Average Contractual Term 6 years 8 months 9 days 6 years 11 months 27 days
Options Outstanding, Aggregate Intrinsic Value $ 23,885 $ 50,021
Time Based Options    
Number of Share Option Awards    
Outstanding as of January 1, 2018 6,580,898  
Granted 0  
Exercised (468,540)  
Forfeited and cancelled (169,000)  
Outstanding as of March 31, 2018 5,943,358 6,580,898
Weighted-Average Exercise Price    
Outstanding as of January 1, 2018 $ 49.18  
Granted 0  
Exercised 33.46  
Forfeited and cancelled 54.75  
Outstanding as of March 31, 2018 $ 50.26 $ 49.18
Performance-Based Awards    
Number of Share Option Awards    
Outstanding as of January 1, 2018 373,969  
Granted 208,335  
Exercised (106,109)  
Forfeited and cancelled (52,084)  
Outstanding as of March 31, 2018 424,111 373,969
Weighted-Average Exercise Price    
Outstanding as of January 1, 2018 $ 31.39  
Granted 59.43  
Exercised 19.00  
Forfeited and cancelled 59.43  
Outstanding as of March 31, 2018 $ 44.82 $ 31.39
Market-Based Awards    
Number of Share Option Awards    
Outstanding as of January 1, 2018 208,333  
Granted 0  
Exercised 0  
Forfeited and cancelled 0  
Outstanding as of March 31, 2018 208,333 208,333
Weighted-Average Exercise Price    
Outstanding as of January 1, 2018 $ 59.43  
Granted 0  
Exercised 0  
Forfeited and cancelled 0  
Outstanding as of March 31, 2018 $ 59.43 $ 59.43