CONDENSED CONSOLIDATED BALANCE SHEETS (unaudited) (Parenthetical) (USD $)	Mar. 31, 2014	Dec. 31, 2013
Stockholders' equity:
Preferred stock, par value (in dollars per share)	$ 0.001	$ 0.001
Preferred stock, shares authorized (in shares)	5,000,000	5,000,000
Preferred stock, shares issued (in shares)	0	0
Preferred stock, shares outstanding (in shares)	0	0
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common stock, shares authorized (in shares)	130,000,000	130,000,000
Common stock, shares issued (in shares)	105,843,137	104,425,614
Common stock, shares outstanding (in shares)	105,793,137	104,375,614
Treasury stock, shares (in shares)	50,000	50,000