Consolidated Balance Sheets (Parentheticals) - USD ($) shares in Millions, $ in Millions	Jun. 30, 2018	Dec. 31, 2017
Statement of Financial Position [Abstract]
Allowance for doubtful accounts	$ 7.1	$ 6.2
Preferred stock, par value (in dollars per share)	$ 0.01	$ 0.01
Preferred stock, authorized (in shares)	100.0	100.0
Preferred stock, issued (in shares)	0.0	0.0
Preferred stock, outstanding (in shares)	0.0	0.0
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	1,000.0	1,000.0
Common stock, shares issued (in shares)	151.5	153.1
Common stock, shares outstanding (in shares)	151.5	153.0
Treasury shares, par value (in dollars per share)	$ 0.01	$ 0.01
Treasury stock, shares held (in shares)	0.0	0.1