Annual report pursuant to Section 13 and 15(d)

Business and Summary of Significant Accounting Principles (Advertising Expense) (Details)

v3.8.0.1
Business and Summary of Significant Accounting Principles (Advertising Expense) (Details) - USD ($)
$ in Millions
12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Accounting Policies [Abstract]      
Advertising expense $ 5.5 $ 7.0 $ 5.7