Warrants (Details) (USD $)	0 Months Ended	12 Months Ended
	Dec. 17, 2012	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Additional information
Closing price of common stock as reported on NASDAQ (in dollars per share)		$ 2.08	$ 2.78	$ 3.48
Warrants
Number of warrants
Outstanding at the beginning of the period (in shares)		221,900
Warrants exercised (number of warrants)		(112,300)
Warrants cancelled (number of warrants)		(109,600)
Outstanding at the end of the period (in shares)			221,900
Weighted-average exercise price
Outstanding at the beginning of the period (in dollars per share)		$ 2.50
Warrants exercised (in dollars per share)		$ 0.90
Warrants cancelled (in dollars per share)		$ 4.14
Outstanding at the end of the period (in dollars per share)			$ 2.50
Weighted-average remaining contractual life (years)
Outstanding at the end of the period			4 months 2 days
Aggregate intrinsic value
Outstanding at the end of the period (in dollars)			$ 224,707
Additional information
Total intrinsic value of warrants exercised during the period (in dollars)		$ 142,625	$ 594,002	$ 2,376,589
Shares issued on warrant exercise (in shares)	917,602	79,677	213,123
Number of shares subject to warrant that were cancelled	464,115	32,623	34,827