Condensed Consolidated Balance Sheets (Parenthetical) - $ / shares	Jun. 30, 2015	Dec. 31, 2014
Common stock, par value	$ 0.001	$ 0.001
Common stock, shares authorized	300,000,000	300,000,000
Common stock, shares issued	120,105,227	119,757,582
Common stock, shares outstanding	115,928,430	115,700,447
Treasury stock, shares	4,176,797	4,057,135