Annual report pursuant to Section 13 and 15(d)

Stock Plans and Management Compensation (Details 2)

v3.20.4
Stock Plans and Management Compensation (Details 2) - Stock Options and SAR's [Member] - $ / shares
12 Months Ended
Dec. 31, 2019
Dec. 31, 2020
Dec. 31, 2018
Dec. 31, 2017
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]        
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price $ 21.57 $ 23.41 $ 16.04 $ 14.40
Age of Grantee 62 years      
$5.87 to $14.68 [Member]        
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]        
Share-based Payment Arrangement, Option, Exercise Price Range, Shares Outstanding   600    
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Exercise Price   $ 14.68    
Greater Than $14.68 [Member]        
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]        
Share-based Payment Arrangement, Option, Exercise Price Range, Shares Outstanding   1,400    
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Exercise Price   $ 21.52    
$23.79 [Member]        
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]        
Share-based Payment Arrangement, Option, Exercise Price Range, Shares Outstanding   19,700    
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Exercise Price   $ 23.79