Condensed Consolidated Balance Sheets (Parenthetical) (USD $) In Millions, except Share data in Thousands, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012
Statement Of Financial Position [Abstract]
Accounts receivable, allowances	$ 11.4	$ 12.9
Preferred stock, par value	$ 0.01	$ 0.01
Preferred stock, shares authorized	5,000	5,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	150,000	150,000
Common stock, shares issued	80,269	79,193
Treasury stock, shares	33,823	33,045