CONSOLIDATED BALANCE SHEETS (Parenthetical) (USD $) In Thousands, except Share data, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Current assets:
Accounts receivable, allowance for doubtful accounts	$ 0	$ 20
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)	14,233,476	13,948,395
Common stock, outstanding (in shares)	14,233,476	13,948,395