Consolidated Statements of Cash Flows - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Cash flows from operating activities:
Net loss	$ (60,461,243)	$ (51,979,610)
Adjustments to reconcile net loss to cash used in operating activities:
Stock-based compensation expense	5,205,792	7,063,941
Depreciation and amortization	255,002	141,733
Loss on disposal of intangible assets		4,610
Change in accrued interest and accretion of discount on short-term investments	(29,633)	(1,240)
Change in operating assets and liabilities:
Prepaid expenses and other current assets	224,458	(1,305,047)
Security deposit	(13,235)	(33,215)
Related party receivable	(531,042)
Long-term prepaid expenses	2,438,022	(2,192,915)
Accounts payable	(653,953)	1,649,735
Accrued expenses	2,177,844	1,093,528
Related party payable	297,366
Net cash used in operating activities	(51,090,622)	(45,558,480)
Cash flows from investing activities:
Purchases of short-term investments	(34,797,004)	(50,011,623)
Proceeds from maturities of short-term investments	5,000,000	45,000,000
Purchases of property and equipment	(57,156)	(33,871)
Software development and other assets	(186,889)	(318,148)
Net cash used in investing activities	(30,041,049)	(5,363,642)
Cash flows from financing activities:
Proceeds from February and October Offerings, net of offering expenses	64,120,736
Proceeds from employee stock purchase plan	131,895	174,762
Proceeds from exercise of options		111,378
Net cash provided by financing activities	86,539,197	286,140
Net increase (decrease) in cash and cash equivalents	5,407,526	(50,635,982)
Cash and cash equivalents, at beginning of period	36,489,618	87,125,600
Cash and cash equivalents, at end of period	41,897,144	36,489,618
Non-cash investing and financing activities:
Offering costs in accrued expenses	69,628
Software development and other costs in accounts payable and accrued expenses	164,922	60,624
Purchase of property and equipment in accounts payable		$ 19,470
ATM [Member]
Cash flows from financing activities:
Proceeds from February and October Offerings, net of offering expenses	$ 22,286,566