Consolidated Balance Sheets (Parenthetical) (USD $)	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Common stock, par value	$ 0.001	$ 0.001
Common stock, shares authorized	300,000,000	300,000,000
Common stock, shares issued	119,077,473	118,502,752
Common stock, shares outstanding	115,382,538	114,949,667
Treasury stock, shares	3,694,935	3,553,085	3,391,592