XML 123 R104.htm IDEA: XBRL DOCUMENT v3.8.0.1
Stock-Based Compensation Plans Narrative (Details) - USD ($)
$ / shares in Units, $ in Millions
12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Statutory tax rate 35.00% 35.00% 35.00%
Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized $ 7.4    
Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized, Period for Recognition 2 years    
Percentage of fair value at purchase date 85.00%    
Discount from market price, purchase date 15.00%    
Employee Option Plan [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Shares reserved for future grants under the stock option and compensation plan 11,100,000    
Directors' Plan [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Shares reserved for future grants under the stock option and compensation plan 360,000    
Restricted Stock/RSUs/PSUs      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Weighted average grant date fair value, options granted (in dollars per share) $ 17.25 $ 11.23 $ 10.66
Expected life of options 3 years 3 years 3 years