Statements of Cash Flows (Unaudited) (USD $)	6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011
Cash flows from operating activities:
Net loss	$ (12,290,626)	$ (10,708,308)
Non-cash items included in net loss:
Depreciation and amortization	107,910	86,490
Change in fair value of common stock warrant liability	369,723	417,860
Stock-based compensation	557,021	559,976
Treasury shares issued for services and 401(k) matching contribution	81,617	28,769
Amortization of deferred financing fees		81,955
Change in deferred rent liability	62,914
Net changes in:
Prepaid expenses and other assets	45,662	(207,339)
Accounts payable	295,457	(1,221,033)
Other accrued liabilities	(141,522)	(436,180)
Net cash used in operating activities:	(10,911,844)	(11,397,810)
Cash flows from investing activities:
Purchases of investment securities	(11,366,148)
Proceeds from sale and maturity of investment securities	9,440,882	301,632
Purchases of property and equipment	(371,215)	(183,490)
Net cash (used in) provided by investing activities	(2,296,481)	118,142
Cash flows from financing activities:
Proceeds from sale of 8% Series A Redeemable, Convertible Preferred Stock, net of issuance costs		4,324,080
Proceeds from sale of common stock equity, net of issuance costs		11,256,456
Proceeds from notes payable	4,853,137
Principal payments on notes payable	(82,556)	(59,716)
Net cash provided by financing activities	4,770,581	15,520,820
(Decrease) increase in cash and cash equivalents	(8,437,744)	4,241,152
Cash and cash equivalents at beginning of period	20,145,854	1,138,916
Cash and cash equivalents at end of period	11,708,110	5,380,068
Supplemental disclosures of cash flow information:
Interest and preferred stock dividends paid	$ 16,275	$ 481,087