XML 104 R80.htm IDEA: XBRL DOCUMENT v3.6.0.2
Share-Based Compensation (Details) - USD ($)
$ in Millions
1 Months Ended 12 Months Ended
Jan. 20, 2017
Feb. 19, 2016
Jan. 15, 2016
Feb. 20, 2015
Jan. 16, 2015
Feb. 21, 2014
Feb. 15, 2013
Jan. 31, 2016
Dec. 31, 2016
Dec. 31, 2015
Dec. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                      
Compensation expense                 $ 3.1 $ 1.0 $ 2.0
Awards forfeited during period, value                 $ 0.0 $ 0.2 $ 0.0
Awards forfeited during period, units                 0 4,676 0
Outstanding awards vested during period                 $ 6.9    
Performance Units [Member]                      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                      
Cash payments distributed related to awards previously granted and now payable               $ 1.2      
Performance Unit Plan [Member] | Performance Units [Member]                      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                      
Award vesting period                 5 years    
Awards granted (in units)   19,055   18,948   21,991 22,884        
Director Incentive Agreement [Member] | Performance Units [Member]                      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                      
Award vesting period                 3 years    
Awards granted (in units)     3,773   3,794            
Director Incentive Agreement [Member] | Performance Units [Member] | Subsequent Event [Member]                      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                      
Awards granted (in units) 4,032