Condensed Consolidated Balance Sheets (Parenthetical) - $ / shares	Jun. 30, 2015	Dec. 31, 2014
Condensed Consolidated Balance Sheets
Preferred stock, par value (in dollars per share)	$ 0.005	$ 0.005
Preferred stock, shares authorized	50,000,000	50,000,000
Common stock, par value (in dollars per share)	$ 0.005	$ 0.005
Common stock, shares authorized	500,000,000	500,000,000
Common stock, shares issued	47,513,468	46,345,376
Common stock, shares outstanding	35,593,544	34,544,653
Treasury stock, shares	11,919,924	11,800,723