Consolidated Statements of Cash Flows (Unaudited) (USD $)	6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010
Cash flows from operating activities:
Net loss	$ (12,729,631)	$ (10,351,943)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	322,920	323,839
Share-based compensation	728,365	276,354
Amortization of investment premium or discount	135,908	305,325
Changes in operating assets and liabilities:
Prepaid expenses and other assets	(418,594)	157,077
Accounts receivable	104,062	(6,795)
Accounts payable and other liabilities	(520,859)	629,575
Accrued expenses	(930,002)	(119,122)
Deferred revenue	(75,000)	175,000
Net cash used in operating activities	(13,382,831)	(8,610,690)
Cash flows from investing activities:
Purchases of property and equipment	(61,571)	(42,848)
Purchases of investments	(41,364,985)	(11,586,670)
Proceeds from maturities of investments	11,000,000	15,506,000
Net cash provided by (used in) investing activities	(30,426,556)	3,876,482
Cash flows from financing activities:
Payments on promissory notes and capital leases	(234,007)	(178,820)
Proceeds from the exercise of stock options and warrants	1,615,336	530,147
Proceeds from the issuance of common stock	50,807,000
Public offering expenses	(219,973)
Net cash provided by financing activities	51,968,356	351,327
Increase (decrease) in cash and cash equivalents	8,158,969	(4,382,881)
Cash and cash equivalents at beginning of period	8,554,151	11,290,332
Cash and cash equivalents at end of period	16,713,120	6,907,451
Supplemental cash flow information:
Interest paid	10,206	21,235
Non-cash financing activities:
Issuance of common stock from cashless warrant exercise	$ 90,431