Condensed Consolidated Balance Sheets (Parenthetical) (USD $) In Millions, except Per Share data	Jun. 30, 2011	Dec. 31, 2010
Condensed Consolidated Balance Sheets
Preferred stock, shares authorized	2.5	2.5
Preferred stock, par value	$ 0.001	$ 0.001
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, shares authorized	100.0	100.0
Common stock, par value	$ 0.001	$ 0.001
Common stock, shares issued	39.1	38.9
Common stock, shares outstanding	39.1	38.9