Condensed Consolidated Balance Sheets (Parenthetical) (USD $) In Millions, except Share data, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011
Preferred stock, par value (in usd per share)	$ 0.01	$ 0.01
Preferred stock, shares authorized (in shares)	10,000,000	10,000,000
Preferred stock, shares issued (in shares)	0	0
Common stock, par value (in usd per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	150,000,000	150,000,000
Common stock, shares issued (in shares)	116,819,000	112,599,000
Common stock, shares outstanding (in shares)	116,819,000	112,599,000
Total assets	$ 167.5	$ 138.2
Total liabilities	$ 63.5	$ 62.4