CONSOLIDATED BALANCE SHEET (Parenthetical) (USD $) In Millions, except Share data, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Accounts receivable, allowance	$ 3.7	$ 0.3
Senior convertible preferred stock, par value	$ 0.01	$ 0.01
Senior convertible preferred stock, shares authorized	10,000,000	10,000,000
Senior convertible preferred stock, shares issued	0	0
Common stock, par value	$ 0.01	$ 0.01
Common stock, share authorized	40,000,000	40,000,000
Common stock, share issued	21,585,129	21,309,210
Treasury stock, shares	951,026	706,161