Statements of Cash Flows (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Cash flows from operating activities:
Net loss	$ (8,251,358)	$ (26,568,382)	$ (23,222,678)
Non-cash items included in net loss:
Depreciation and amortization	339,229	281,489	169,358
Change in fair value of common stock warrant liability	(8,090,636)	4,117,534	(81,733)
Cash received for non-refundable research and development fee	5,000,000
Deferred revenue	(500,000)
Stock based compensation - options	1,215,971	1,084,326	1,036,337
Stock based compensation – restricted stock	19,466	59,438	171,549
Shares issued out of treasury	62,546	57,239	60,360
Amortization of patent license fee	7,500	7,500	7,500
Shares issued in exchange for services	35,500	49,810	71,550
Deferred finance charges	336,387	43,215
Change in deferred rent liability	(18,940)	55,256	65,467
Net changes in:
Prepaid expenses and other	(121,235)	585,595	(393,676)
Deposits and other assets	(116,181)	18,721	4,167
Accounts payable	(887,332)	(1,344,379)	(538,383)
Other accrued liabilities	1,497,566	(776,955)	(92,255)
Net cash used in operating activities	(9,471,517)	(22,329,593)	(22,742,437)
Cash flows from investing activities:
Purchases of investment securities	(66,376,818)	(16,208,958)	(10,659,238)
Proceeds from sale and maturity of investment securities	37,194,375	18,478,591	395,556
Refund (deposit) on security for letter of credit	50,000		(250,000)
Purchases of property and equipment	(57,494)	(613,390)	(573,406)
Net cash (used in) provided by investing activities	(29,189,937)	1,656,243	(11,087,088)
Cash flows from financing activities:
Proceeds from sale of preferred stock, net of issuance costs	13,616,432		4,324,080
Proceeds from sale of common stock equity, net of issuance costs	15,622,955		48,082,025
Proceeds from exercise of common stock options	184,047	697,220
Proceeds from note payable	4,763,803	4,825,494	144,448
Principal payments on note payable	(5,060,711)	(110,287)	(142,427)
Net cash provided by financing activities	29,388,470	15,518,984	52,836,463
(Decrease) Increase in cash and cash equivalents	(9,272,984)	(5,154,366)	19,006,938
Cash and cash equivalents at beginning of period	14,991,488	20,145,854	1,138,916
Cash and cash equivalents at end of period	5,718,504	14,991,488	20,145,854
Cash paid for:
Interest	637,183	359,413	501,855
Common Stock Warrants (Member)
Cash flows from financing activities:
Proceeds from exercise of common stock warrants	$ 261,944	$ 10,106,557	$ 428,337