XML 69 R58.htm IDEA: XBRL DOCUMENT v3.21.2
Share-Based Compensation - Stock Option Activity under Company's Plan - Long Term Incentive Plan (Detail) - Long Term Incentive Plan Stock Option [Member] - USD ($)
$ / shares in Units, $ in Thousands
9 Months Ended
Sep. 30, 2021
Sep. 30, 2020
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Outstanding at January 1, 2021, Number of Shares 50,950  
Granted, Number of Shares 3,000 25,500
Exercised, Number of Shares (7,000) (3,750)
Forfeited, Number of Shares 0  
Outstanding (vested and expected to vest) at September 30, 2021, Number of Shares 46,950  
Exercisable at September 30, 2021, Number of Shares 27,450  
Outstanding at January 1, 2021, Weighted Average Exercise Price per Share $ 54.81  
Granted, Weighted Average Exercise Price per Share 69.89  
Exercised, Weighted Average Exercise Price per Share 47.66  
Outstanding (vested and expected to vest) at September 30, 2021, Weighted Average Exercise Price per Share 56.84  
Exercisable at September 30, 2021, Weighted Average Exercise Price per Share $ 58.91  
Outstanding (vested and expected to vest) at September 30, 2021, Weighted Average Remaining Contractual Term 6 years 8 months 12 days  
Exercisable at September 30, 2021, Weighted Average Remaining Contractual Term 5 years 2 months 12 days  
Outstanding (vested and expected to vest) at September 30, 2021, Aggregate Intrinsic Value $ 465  
Exercisable at September 30, 2021, Aggregate Intrinsic Value $ 234