Issuance of Common Stock (Details) (USD $)	6 Months Ended		3 Months Ended						1 Months Ended		3 Months Ended						6 Months Ended	3 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012 Class A Common Stock Stock Options	Mar. 31, 2012 Class A Common Stock Stock Options	Jun. 30, 2012 Class A Common Stock Stock Options Minimum	Mar. 31, 2012 Class A Common Stock Stock Options Minimum	Jun. 30, 2012 Class A Common Stock Stock Options Maximum	Mar. 31, 2012 Class A Common Stock Stock Options Maximum	Jun. 30, 2012 Class A Common Stock 2004 Employee Stock Purchase Plan	Jun. 02, 2012 Class A Common Stock 2004 Employee Stock Purchase Plan	Jun. 30, 2012 Class A Common Stock Warrants - April 2009 financing	Jun. 30, 2012 Class A Common Stock SRA Warrants - April 2009 financing	Jun. 30, 2012 Class A Common Stock Warrants - March and April 2009 financings	Jun. 30, 2012 Class A Common Stock SRA Warrants - March 2009 financing	Jun. 30, 2012 Class A Common Stock At the market offerings through MLV	Mar. 31, 2012 Class A Common Stock At the market offerings through MLV	Jun. 30, 2012 Class A Common Stock At the market offerings through MLV	Jun. 30, 2012 Class A Common Stock At the market offerings through MLV Minimum	Mar. 31, 2012 Class A Common Stock At the market offerings through MLV Minimum	Jun. 30, 2012 Class A Common Stock At the market offerings through MLV Maximum	Mar. 31, 2012 Class A Common Stock At the market offerings through MLV Maximum
Issuance of Common Stock
Net proceeds from issuance of common stock	$ 5,143,876														$ 2,784,494	$ 2,359,382	$ 5,100,000
Offering costs															89,000	75,000	164,000
Gross proceeds received from exercise of warrants	291,500	991,239									173,250		118,250
Issuance of shares upon exercise of warrants											315,000	27,143	215,000	13,299
Warrants, exercise price (in dollars per share)											$ 0.55		$ 0.55	$ 0.55
Proceeds from employee stock option exercises	66,497	771,815	5,945	60,552
Employee stock options exercised (in shares)			9,700	65,432
Exercise price of employee stock options exercised (in dollars per share)					$ 0.52	$ 0.81	$ 0.81	$ 1.95										$ 0.68	$ 2.10	$ 1.89	$ 2.28
Issuance of shares									557,922						2,479,501	1,114,241
Share price (in dollars per share)										$ 0.85					$ 1.48		$ 1.48
Proceeds from employee stock purchase plan	$ 474,233	$ 436,771							$ 474,233