Quarterly report pursuant to Section 13 or 15(d)

Employee Stock Plans - Additional Information (Details)

v3.20.2
Employee Stock Plans - Additional Information (Details)
$ / shares in Units, $ in Thousands
3 Months Ended 6 Months Ended
Jun. 30, 2020
USD ($)
item
$ / shares
shares
Jun. 30, 2019
USD ($)
Jun. 30, 2020
USD ($)
$ / shares
Jun. 30, 2019
USD ($)
Additional Employee Stock Plans Information        
Income tax benefit $ (17,456) $ 8,299 $ (20,718) $ 7,836
Performance Share Unit Awards | 2010 Plan        
Additional Employee Stock Plans Information        
Vesting period of awards 2 years      
Compensation expenses recognized $ 268 769 752 1,063
Unrecognized compensation expense, net of expected forfeitures, calculated under the fair value method for shares expected to vest $ 1,126   $ 1,126  
Performance period 3 years      
Restricted stock units        
Additional Employee Stock Plans Information        
fair value per share of the awards | $ / shares $ 53.50   $ 50.26  
Compensation expenses recognized $ 933 713    
Restricted stock units | Non-employee director        
Additional Employee Stock Plans Information        
Number of shares issued upon exercise of units other than options | shares 1      
Restricted stock units | 2010 Plan        
Additional Employee Stock Plans Information        
Compensation expenses recognized     $ 1,817 1,473
Unrecognized compensation expense, net of expected forfeitures, calculated under the fair value method for shares expected to vest $ 1,252   1,252  
Minimum age of employee, attaining which awards are continued to be vested upon retirement | item 65      
Minimum service period, upon serving which awards are continued to be vested upon retirement 10 years      
Minimum age of employee along with service period condition, attaining which awards are continued to be vested upon retirement | item 55      
Maximum period following a termination of service in which the share-based award will be settled 2 months 15 days      
Restricted stock units | 2010 Plan | Management        
Additional Employee Stock Plans Information        
Accelerated stock based compensation expense $ 659 $ 1,031 $ 962 $ 1,374
Restricted stock units | 2010 Plan | Common Stock        
Additional Employee Stock Plans Information        
Number of shares issued upon exercise of units other than options | shares 1