CONDENSED STATEMENTS OF CASH FLOWS - USD ($)	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Operating activities
Net income (loss)	$ (8,602,646)	$ (11,488,585)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation	202,644	238,347
Stock-based compensation	1,355,800	1,132,519
Loss on disposal of property and equipment	(1,213)	2,222
Amortization of Debt Discount (Premium)	(192,298)
Accretion of bond premium		43,001
Change in operating assets and liabilities:
Receivables	177,731	22,435
Prepaid expenses and other assets	(337,374)	396,962
Accounts payable	863,915	(3,085)
Accrued wages, benefits and other liabilities	(1,155,713)	(814,721)
Deferred revenue	(15,855)	(12,500)
Net cash used in operating activities	(7,705,009)	(10,483,405)
Investing activities
Purchases of property and equipment	(5,225)	(29,536)
Proceeds from disposal of property and equipment	46,580
Purchases of investments	27,703,624	14,977,694
Proceeds from sale and maturities of investments	23,500,000	28,000,000
Net cash provided by investing activities	(4,162,269)	12,992,770
Financing activities
Stock repurchase	(104,462)	(92,929)
Proceeds from issuance of common stock in connection with equity offering	80,941,381
Proceeds from the exercise of stock options	2,302,973	16,290
Net cash provided by financing activities	83,139,892	(76,639)
Net increase (decrease) in cash and cash equivalents	71,272,614	2,432,726
Cash and cash equivalents at beginning of period	18,559,130	31,228,192
Cash and cash equivalents at end of period	$ 89,831,744	$ 33,660,918