Summary of Common Stock Warrants - A, B, C, D (Details)	Series A	Series B	Series C	Series D	A,B,C,D Total Warrants
Outstanding at Dec. 31, 2012	1,188,909	7,952,313	128,180	15,312,627	24,582,029
Issued					0
Exercised		(2,619,332)			(2,619,332)
Outstanding at Dec. 31, 2013	1,188,909	5,332,981	128,180	15,312,627	21,962,697
Issued					0
Exercised	(1,188,909)	(5,328,481)	(128,180)	(807,861)	(7,453,431)
Outstanding at Dec. 31, 2014		4,500		14,504,766	14,509,266