Quarterly report pursuant to Section 13 or 15(d)

Employee Stock Plans - Additional Information (Details)

v3.21.2
Employee Stock Plans - Additional Information (Details)
$ / shares in Units, $ in Thousands
 3 Months Ended 6 Months Ended
Jun. 30, 2021
USD ($)
Jun. 30, 2020
USD ($)
Jun. 30, 2021
USD ($)
item
$ / shares
shares
Jun. 30, 2020
USD ($)
Additional Employee Stock Plans Information        
Income tax expense (benefit) $ 816 $ (17,456) $ 739 $ (20,718)
Performance Share Unit Awards | 2010 Plan        
Additional Employee Stock Plans Information        
fair value per share of the awards | $ / shares     $ 49.96  
Compensation expenses recognized 2,463 268 $ 3,274 752
Unrecognized compensation expense, net of expected forfeitures, calculated under the fair value method for shares expected to vest 2,603   $ 2,603  
Performance period     3 years  
Restricted stock units        
Additional Employee Stock Plans Information        
fair value per share of the awards | $ / shares     $ 44.49  
Compensation expenses recognized 1,592 933 $ 2,746 1,817
Restricted stock units | Nonemployee Director [Member]        
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        
Unrecognized compensation expense, net of expected forfeitures, calculated under the fair value method for shares expected to vest 2,046   $ 2,046  
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 $ 3,286 $ 659 $ 4,145 $ 962
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