Quarterly report pursuant to Section 13 or 15(d)

Employee Stock Plans - Additional Information (Details)

v3.21.1
Employee Stock Plans - Additional Information (Details)
$ / shares in Units, $ in Thousands
3 Months Ended
Mar. 31, 2021
USD ($)
item
$ / shares
shares
Mar. 31, 2020
USD ($)
Additional Employee Stock Plans Information    
Income tax expense (benefit) $ (77) $ (3,262)
Performance Share Unit Awards | 2010 Plan    
Additional Employee Stock Plans Information    
fair value per share of the awards | $ / shares $ 49.96  
Compensation expenses recognized $ 811 484
Unrecognized compensation expense, net of expected forfeitures, calculated under the fair value method for shares expected to vest $ 4,807  
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 $ 1,154 884
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 $ 3,575  
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 $ 859 $ 303
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