Consolidated Balance Sheets (Parenthetical) (USD $) In Millions, except Share data, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Statement Of Financial Position [Abstract]
Trade receivables, net of allowance for doubtful accounts	$ 28.8	$ 31.4
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	224,683,653	205,707,580
Common stock, shares outstanding	210,531,894	196,198,672
Common stock reserved for issuance related to Settlement agreement, par value per share	$ 0.10	$ 0.10
Common stock reserved for issuance related to Settlement agreement, shares	0	18,000,000
Common stock in treasury, shares	14,151,759	9,508,908