Statements of Cash Flows (Unaudited) (USD $)	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Cash flows from operating activities:
Net loss	$ (650,974)	$ (6,186,241)
Non-cash items included in net income (loss):
Depreciation and amortization	76,875	53,955
Change in fair value of common stock warrant liability	(4,280,297)	(77,600)
Deferred revenue	4,875,000
Stock-based compensation	263,192	305,127
Treasury shares issued for services and 401(k) matching contribution	20,835	50,384
Change in deferred rent liability	(3,829)	65,467
Net changes in:
Accrued interest on short term investments and other current assets	(194,100)	(216,934)
Accounts payable	1,841,037	(301,358)
Accrued liabilities	(157,534)	579,323
Net cash provided by (used in) operating activities:	1,790,205	(5,727,877)
Cash flows from investing activities:
Purchases of investment securities	(20,245,204)	(10,309,461)
Proceeds from sale and maturity of investment securities	3,048,000	5,237,504
Purchases of property and equipment		(177,600)
Net cash used in investing activities	(17,197,204)	(5,249,557)
Cash flows from financing activities:
Proceeds from sale of Preferred Stock, net of issuance costs	13,648,663
Proceeds from sale of common stock equity, net of issuance costs	6,711,173
Proceeds from exercise of common stock warrants	200,000
Proceeds from exercise of options to purchase common stock	174,871
Principal payments on notes payable	(14,461)	(46,341)
Net cash provided by (used in) financing activities	20,782,190	(46,341)
Increase (decrease) in cash and cash equivalents	5,375,191	(11,023,775)
Cash and cash equivalents at beginning of period	14,991,488	20,145,854
Cash and cash equivalents at end of period	20,366,679	9,122,079
Supplemental disclosures of cash flow information:
Interest paid	180,928	5,701
Common Stock Warrants (Member)
Cash flows from financing activities:
Proceeds from exercise of common stock warrants	$ 261,944