Net income (loss) per share (Details 1)	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Potential shares of common stock excluded from diluted net income per share
Options to purchase common shares	3,454,660	3,200,650	1,532,910	3,200,650
Outstanding warrants	17,443,727	17,843,727	17,443,727	17,843,727
MHR convertible note payable	8,087,809	7,246,873	8,087,809	7,246,873
Potential shares of common stock excluded from diluted net income per share	28,986,196	28,291,250	27,064,446	28,291,250