XML 112 R99.htm IDEA: XBRL DOCUMENT v3.10.0.1
Retirement and Share-based Compensation Plans (Incentive Plans) (Details) - shares
12 Months Ended
Dec. 31, 2018
Dec. 31, 2017
Dec. 31, 2016
2016 Employee Incentive Plan      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Number of shares authorized 2,500,000    
Number of shares available for future grant 1,967,395    
2016 Employee Incentive Plan | Performance Units      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Award vesting period 3 years    
Equity instruments granted 105,617 84,476 208,565
Duration used to measure performance and threshold goals 3 years    
2016 Employee Incentive Plan | Performance Units | Threshold Goals, Vesting Percentage | 2018 Employee Grant      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Award vesting rights, percentage 50.00%    
2016 Employee Incentive Plan | Performance Units | Threshold Goals, Vesting Percentage | 2017 Employee Grant      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Award vesting rights, percentage 50.00%    
2016 Employee Incentive Plan | Performance Units | Threshold Goals, Vesting Percentage | 2016 Employee Grant      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Award vesting rights, percentage 50.00%    
2016 Employee Incentive Plan | Performance Units | Target Performance Goals, Vesting Percentage | 2018 Employee Grant      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Award vesting rights, percentage 100.00%    
2016 Employee Incentive Plan | Performance Units | Target Performance Goals, Vesting Percentage | 2017 Employee Grant      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Award vesting rights, percentage 100.00%    
2016 Employee Incentive Plan | Performance Units | Target Performance Goals, Vesting Percentage | 2016 Employee Grant      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Award vesting rights, percentage 100.00%    
2016 Employee Incentive Plan | Performance Units | Maximum Performance Goals, Vesting Percentage | 2018 Employee Grant      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Award vesting rights, percentage 150.00%    
2016 Employee Incentive Plan | Performance Units | Maximum Performance Goals, Vesting Percentage | 2017 Employee Grant      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Award vesting rights, percentage 150.00%    
2016 Employee Incentive Plan | Restricted Stock      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Award vesting period 3 years    
Shares issued in period 36,270 39,826 43,373
Participant age for full vesting 65 years    
Requisite service period for full vesting 10 years    
2016 Employee Incentive Plan | Restricted Stock | 2016 Revised Grant      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Shares issued in period     21,806
2016 Employee Incentive Plan | Restricted Stock | Share-based Compensation Award, Tranche One | 2017 Employee Grant      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Award vesting period   1 year  
Shares issued in period   6,727  
2016 Employee Incentive Plan | Restricted Stock Units      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Award vesting period 1 year    
Equity instruments granted 85,500    
2016 Employee Incentive Plan | Restricted Stock Units | Share-based Compensation Award, Tranche One      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Award vesting period 3 years    
Equity instruments granted 6,000    
2009 Employee Incentive Plan      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Number of shares authorized 2,500,000    
Duration of award 10 years    
Award vesting period 3 years    
2009 Employee Incentive Plan | March 2010 Option Grant      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Duration of award 6 years    
2013 Director Equity And Incentive Plan      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Number of shares authorized 250,000    
Number of shares available for future grant 54,900    
2013 Director Equity And Incentive Plan | Restricted Stock      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Shares issued in period 28,600 33,000 47,500
Maximum | 2013 Director Equity And Incentive Plan      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Award vesting period 1 year