CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Current assets:
Accounts receivable, allowance for doubtful accounts	$ 19	$ 6
Stockholders' equity:
Common stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Common stock, shares authorized (in shares)	50,000,000	50,000,000
Common stock, shares issued (in shares)	19,030,024	18,717,439
Common stock, shares outstanding (in shares)	18,548,180	18,286,961
Treasury stock (in shares)	481,844	430,478