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Share-Based Compensation Plans - Additional information (Details) - USD ($)
3 Months Ended 9 Months Ended
Sep. 30, 2021
Mar. 31, 2021
Sep. 30, 2020
Sep. 30, 2021
Sep. 30, 2020
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Allocated Share-based Compensation Expense $ 338,000   $ 362,000 $ 1,210,000 $ 1,063,000
Additional share based compensation expense   $ 232,000      
Incentive Plan 2015 [Member] | Employee Stock Option          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Extension of expiration period of stock options       2 years  
Incentive Plan 2016 [Member] | Employee Stock Option          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Extension of expiration period of stock options       1 year