Issuance of Common Stock (Details) (USD $)	3 Months Ended								3 Months Ended		3 Months Ended						0 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Mar. 31, 2013 Class A Common Stock	Mar. 31, 2013 Class A Common Stock Stock Options	Mar. 31, 2012 Class A Common Stock Stock Options	Mar. 31, 2012 Class A Common Stock Minimum	Mar. 31, 2012 Class A Common Stock Maximum	Mar. 31, 2012 Class A Common Stock SRA Warrants - 2009 financing	Mar. 31, 2012 Class A Common Stock Warrants - March and April 2009 financings	Mar. 13, 2013 Class A Common Stock Warrants Issued, March 2013	Mar. 31, 2013 Class A Common Stock At the market offerings through MLV	Mar. 31, 2012 Class A Common Stock At the market offerings through MLV	Mar. 31, 2013 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	Mar. 31, 2013 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	Mar. 13, 2013 Class A Common Stock Equity issuance
Common Stock
Number of shares sold											379,950	1,114,241					1,204,820
Share price (in dollars per share)													$ 0.70	$ 2.10	$ 0.73	$ 2.28	$ 0.83
Gross proceeds from issuance of common stock																	$ 1,000,000
Placement agent fees equal to gross proceeds from offering (as a percent)																	6.00%
Net proceeds from issuance of common stock	1,172,946	2,359,382									262,945	2,359,382					910,000
Placement agent fees																	60,000
Legal and other fees																	30,000
Number of shares under warrants										602,410
Exercise price of warrants (in dollars per share)								$ 0.55	$ 0.55	$ 0.83
Offering costs											8,700	75,000
Gross proceeds received from exercise of warrants		118,250							118,250
Issuance of shares upon exercise of warrants									215,000
Proceeds from employee stock option exercises	$ 42,039	$ 60,552		$ 42,039	$ 60,552
Issuance of shares upon exercise of employee stock options				51,933	65,432
Exercise price of employee stock options exercised (in dollars per share)			$ 0.81			$ 0.81	$ 1.95