Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($)	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Cash flows from operating activities:
Net loss	$ (5,716,467)	$ (7,005,068)
Depreciation and amortization	$ 121,875	109,875
Change in fair value of common stock warrant liability		43,228
Change in fair value of earn-out milestone liability	$ 302,656	172,136
Deferred revenue	(125,000)	(125,000)
Stock-based compensation costs	615,014	848,843
Shares issued out of treasury	20,951	26,736
Amortization of deferred finance charges and debt discount associated with notes payable	85,192	127,392
Change in deferred rent liability	(8,813)	(6,546)
Loss (gain) realized on sale of investment securities	3,858	(129)
Accrued interest on short term investments	26,729	172,328
Prepaid expenses, deposits and other assets	(182,102)	(399,774)
Accounts payable	65,286	(632,437)
Accrued liabilities	177,272	(532,781)
Net cash (used in) operating activities:	$ (4,744,121)	(5,936,323)
Cash flows from investing activities:
Purchases of investment securities		(15,277,192)
Proceeds from sale and maturity of investment securities	$ 10,799,890	17,062,532
Purchases of property and equipment	(21,878)	(43,174)
Net cash provided by investing activities	10,778,012	1,742,166
Cash flows from financing activities:
Principal payments on notes payable	(988,493)	(878,437)
Net cash (used in) financing activities	(988,493)	(878,437)
Increase (decrease) in cash and cash equivalents	5,045,398	(5,072,594)
Cash and cash equivalents at beginning of period	9,265,144	12,686,881
Cash and cash equivalents at end of period	14,310,542	7,614,287
Supplemental disclosures of cash flow information:
Interest paid	$ 165,527	$ 264,911