Balance Sheet Parenthetical (Parentheticals) - USD ($) shares in Millions, $ in Millions	Sep. 30, 2017	Dec. 31, 2016
Allowance for Doubtful Accounts Receivable, Current	$ 3.7	$ 5.8
Preferred Stock, Value, Issued	$ 0.0	$ 0.0
Preferred Stock, Shares Authorized	5.0	5.0
Preferred Stock, Shares Outstanding	0.0	0.0
Common Stock, Par or Stated Value Per Share	$ 0.0	$ 0.0
Common Stock, Shares Authorized	500.0	500.0
Common Stock, Shares, Issued	191.5	191.0
Common Stock, Shares, Outstanding	92.4	94.7
Treasury Stock, Shares	99.1	96.3