Condensed Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Millions	Sep. 30, 2018	Dec. 31, 2017
Statement of Financial Position [Abstract]
Allowance for doubtful accounts	$ 7.2	$ 6.5
Inventory reserves	$ 19.9	$ 15.5
Preferred stock, par value per share (in dollars per share)	$ 0.10	$ 0.10
Preferred stock, shares authorized	50,000,000	50,000,000
Preferred stock, shares issued	0	0
Common stock, par value per share (in dollars per share)	$ 0.10	$ 0.10
Common stock, shares authorized	400,000,000	400,000,000
Common stock, shares issued	231,609,331	230,080,944
Common stock, shares outstanding	156,936,418	168,595,521
Common stock in treasury, shares	74,672,913	61,485,423