Condensed Consolidated Balance Sheets (Parenthetical) (USD $)	Mar. 31, 2014	Dec. 31, 2013
Common stock, par value	$ 0.001	$ 0.001
Common stock, shares authorized	300,000,000	300,000,000
Common stock, shares issued	119,719,108	119,077,473
Common stock, shares outstanding	115,689,880	115,382,538
Treasury stock, shares	4,029,228	3,694,935