Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($)	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Cash flows from operating activities:
Net loss	$ (7,085,162)	$ (25,402,401)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	271,494	348,843
Stock-based compensation expense	934,510	1,731,484
Fair value adjustment on warrant liabilities	(527,025)	4,336,066
Amortization of loan cost and discount	883,153	975,743
Loss on retirement of fixed assets		421,843
Changes in assets and liabilities:
Receivables	1,378,019	136,072
Prepaid expenses and other current assets	1,686,369	1,662,994
Accounts payable	(2,488,589)	673,635
Accrued expenses and other current liabilities	(670,497)	(1,026,781)
Net cash used in operating activities	(5,617,728)	(16,142,502)
Cash flows from investing activities:
Purchases of equipment and furnishings	(9,194)	(134,598)
Net cash used in investing activities	(9,194)	(134,598)
Cash flows from financing activities:
Proceeds from public offering	6,512,151	13,951,218
Payment of principal on term loan	(2,102,341)	(2,427,362)
Net proceeds from exercise of warrants and stock options		2,766,605
Net cash provided by financing activities	4,409,810	14,290,461
Net decrease in cash and cash equivalents	(1,217,112)	(1,986,639)
Cash and cash equivalents at beginning of period	37,643,404	56,959,485
Cash and cash equivalents at end of period	36,426,292	54,972,846
Supplemental disclosure of cash flow information:
Cash paid during the year for interest	487,328	1,212,219
Cash paid for income taxes	800	800
Supplemental disclosure of non-cash activities:
Warrant liability exercise		1,558,377
Preferred stock conversion		$ 7,400