Condensed Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Millions	Sep. 30, 2015	Dec. 31, 2014
Statement Of Financial Position [Abstract]
Trade receivables, net of allowance for doubtful accounts	$ 26.1	$ 28.8
Preferred stock, par value 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	$ 0.10	$ 0.10
Common stock, shares authorized	400,000,000	400,000,000
Common stock, shares issued	225,612,687	224,683,653
Common stock, shares outstanding	197,651,615	210,531,894
Common stock in treasury, shares	27,961,072	14,151,759
Assets held for sale		$ 42.0
Liabilities held for sale		$ 6.0