Condensed Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Millions	Jun. 30, 2017	Dec. 31, 2016
Statement Of Financial Position [Abstract]
Accounts Receivable, allowances (in dollars)	$ 11.4	$ 11.1
Preferred stock authorized (in shares)	3,500,000	3,500,000
Par value of preferred stock per share (in dollars per share)	$ 0.01	$ 0.01
Preferred stock outstanding (in shares)	0	0
Common stock, shares authorized (in shares)	300,000,000	300,000,000
Common stock, shares issued (in shares)	163,175,928	163,175,928
Common stock, shares outstanding (in shares)	140,734,391	139,841,214
Treasury stock (in shares)	22,441,537	23,334,714