Condensed Consolidated Balance Sheets (Parenthetical) (USD $) In Millions, except Share data	Jun. 30, 2011	Dec. 31, 2010
Current assets:
Receivables, allowance for doubtful accounts	$ 16.9	$ 17.0
Stockholders' equity:
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	170,648,419	169,272,636
Common stock, shares outstanding	160,210,558	159,305,507
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	18,000,000	18,000,000
Common stock in treasury, shares	10,437,861	9,967,129