CONDENSED CONSOLIDATED BALANCE SHEETS (unaudited) (Parenthetical) (USD $)	Mar. 31, 2013	Dec. 31, 2012
Stockholders' equity:
Convertible preferred stock, par value (in dollars per share)	$ 0.001	$ 0.001
Convertible preferred stock, authorized (in shares)	5,000,000	5,000,000
Convertible preferred stock, issued (in shares)	0	0
Convertible preferred stock, outstanding (in shares)	0	0
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common stock, authorized (in shares)	50,000,000	50,000,000
Common stock, issued (in shares)	14,671,912	14,233,476
Common stock, outstanding (in shares)	14,671,912	14,233,476