Condensed Consolidated Statements of Cash Flows - USD ($)	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
CASH FLOWS FROM OPERATING ACTIVITIES:
Net loss	$ (87,616,245)	$ (54,578,751)
Adjustments to reconcile net loss to net cash used in operating activities:
Gain on sale of long-term securities	0	(33,042)
Noncash stock compensation expense	12,375,306	6,181,400
Depreciation	62,009	42,464
Amortization of premium on investment securities	53,860	367,673
Change in fair value of notes payable	113,281	(63,822)
Changes in assets and liabilities:
Increase in restricted cash	(3,051)	(3,041)
Decrease (increase) in other current assets	147,826	(1,162,310)
Decrease (increase) in leasehold interest	88,179	(2,517,771)
Decrease in accrued interest receivable	83,852	77,563
Decrease (increase) in other assets	161,730	(3,523)
Increase in accounts payable and accrued expenses	2,666,164	6,447,215
Increase in deferred rent	72,942	793,968
Decrease in deferred revenue	(114,286)	(114,286)
Net cash used in operating activities	(71,908,433)	(44,566,263)
CASH FLOWS FROM INVESTING ACTIVITIES:
Purchases of property, plant and equipment	(2,227)	(323,015)
Investment in held-to-maturity securities	0	(15,199,922)
Proceeds from the sale of long-term securities	0	18,000,000
Proceeds from maturity of short-term securities	19,800,000	12,589,219
Net cash provided by investing activities	19,797,773	15,066,282
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from the exercise of warrants	2,143,085	100,896
Proceeds from sale of common stock, net	116,778,462	3,504,261
Financing costs	0	(9,984)
Net cash provided by financing activities	118,921,547	3,595,173
NET INCREASE (DECREASE) IN CASH AND CASH EQUIVALENTS	66,810,887	(25,904,808)
CASH AND CASH EQUIVALENTS AT BEGINNING OF PERIOD	25,031,280	55,061,329
CASH AND CASH EQUIVALENTS AT END OF PERIOD	91,842,167	29,156,521
NONCASH TRANSACTIONS
Reclassification of deferred financing costs to additional paid-in capital	(2,645)	(56,988)
Conversion of convertible notes payable to common stock	$ 0	$ 30,601