XML 118 R102.htm IDEA: XBRL DOCUMENT v3.20.4
Share-Based Arrangements (Employee Stock Purchase Plan) (Details) - ESPP Stock - $ / shares
12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award      
Market price after discount, purchase date 85.00%    
Number of shares authorized (in shares) 2,000,000    
Employee stock issued (in shares) 47,524 60,997 59,082
Number of shares available for purchase (in shares) 503,588    
Minimum [Member]      
Share-based Compensation Arrangement by Share-based Payment Award      
Employee stock issued (in dollars per share) $ 38.47 $ 55.61 $ 56.86
Maximum [Member]      
Share-based Compensation Arrangement by Share-based Payment Award      
Employee stock issued (in dollars per share) $ 65.92 $ 63.69 $ 72.15