CONSOLIDATED BALANCE SHEETS (Parenthetical) (USD $) In Millions, except Share data, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010
Accounts receivable, allowance	$ 6.9	$ 5.9
Preferred stock, par value	$ 0.01	$ 0.01
Preferred stock, shares authorized	10,000,000	10,000,000
Preferred stock, issued
Preferred stock, outstanding
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	140,000,000	140,000,000
Common stock, issued	37,059,236	37,024,842
Common stock, outstanding	37,058,507	37,024,842