XML 102 R89.htm IDEA: XBRL DOCUMENT v3.8.0.1
Stock-Based Compensation - Stock-Based Compensation Expense (Details) - USD ($)
$ in Millions
12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]      
Compensation expense $ 10.1 $ 5.5 $ 2.7
Income tax benefit (2.5) (2.1) (1.1)
Total $ 7.6 $ 3.4 $ 1.6