XML 123 R108.htm IDEA: XBRL DOCUMENT v3.20.4
Stock plans - Schedule of Activity Related to Restricted Stock (Details) - Restricted Stock - shares
12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award      
Nonvested, January 1 25,984 12,892 1,538
Granted shares 16,269 17,345 11,468
Vested shares 8,455 2,542 114
Forfeited shares 1,875 1,711  
Nonvested, December 31 31,923 25,984 12,892