Net income (loss) per share (Details) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Numerator:
Net loss	$ (808,554)	$ (3,961,815)	$ (131,947)	$ (4,333,290)
Net loss applicable to common stockholders - basic	(808,554)	(3,961,815)	(131,947)	(4,333,290)
Net loss applicable to common stockholders - diluted	$ (808,554)	$ (3,961,815)	$ (131,947)	$ (4,333,290)
Denominator:
Weighted average common stock outstanding (basic) (in shares)	53,051,626	52,366,739	52,888,734	52,062,429
Weighted average common stock outstanding (diluted) (in shares)	53,051,626	52,366,739	52,888,734	52,062,429
Basic net loss per share applicable to common stockholders (in dollars per share)	$ (0.02)	$ (0.08)	$ 0.00	$ (0.08)
Diluted net loss per share applicable to common stockholders (in dollars per share)	$ (0.02)	$ (0.08)	$ 0.00	$ (0.08)
Anti-dilutive securities excluded from computation of diluted earnings per share
Total anti-dilutive securities (in shares)	16,156,239	17,680,428	15,911,890	17,455,200
Contingently issued restricted shares | First restricted stock grant
Anti-dilutive securities excluded from computation of diluted earnings per share
Total anti-dilutive securities (in shares)	915,000	915,000	915,000	915,000
Contingently issued restricted shares | Second restricted stock grant
Anti-dilutive securities excluded from computation of diluted earnings per share
Total anti-dilutive securities (in shares)	468,941		468,941
Stock options
Anti-dilutive securities excluded from computation of diluted earnings per share
Total anti-dilutive securities (in shares)	8,507,266	8,720,709	8,369,974	8,495,481
Restricted stock awards
Anti-dilutive securities excluded from computation of diluted earnings per share
Total anti-dilutive securities (in shares)	206,642		96,036
Warrants
Anti-dilutive securities excluded from computation of diluted earnings per share
Total anti-dilutive securities (in shares)	591,187	2,108,575	594,736	2,108,575
Convertible preferred stock
Anti-dilutive securities excluded from computation of diluted earnings per share
Total anti-dilutive securities (in shares)	6,851,144	6,851,144	6,851,144	6,851,144