Statements of Cash Flows - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Cash flows from operating activities:
Net loss	$ (40,868,006)	$ (50,859,803)
Adjustments to reconcile net loss to net cash used in operating activities:
Stock-based compensation expense	7,469,442	6,182,841
Stock-based 401K company common match	145,167	217,536
Depreciation expense	174,347	182,918
Impairment of machinery and equipment	2,822,581	0
Amortization of debt discount	1,039	32,869
Amortization of debt issuance costs	125,355	108,407
Non-cash interest expense	405,278	363,909
Changes in assets and liabilities:
Prepaid expenses and other assets	(18,909)	(32,099)
Accounts payable	(3,969,686)	898,101
Accrued expenses	(5,003,087)	2,208,490
Restructuring reserve	5,563,186	0
Net cash used in operating activities	(33,153,293)	(40,696,831)
Cash flows from investing activities:
Purchases of property and equipment	0	(188,721)
Net cash used in investing activities	0	(188,721)
Cash flows from financing activities:
Proceeds from issuance of debt	0	5,000,000
Proceeds from exercise of stock options	721,195	118,188
Proceeds from exercise of warrants	0	53,149
Payments for debt back end fees	(990,000)	0
Repayment of debt	(20,000,000)	0
Proceeds from issuance of common stock, net of underwriting costs	0	17,382,943
Net cash (used in) provided by financing activities	(20,268,805)	22,554,280
Net decrease in cash	(53,422,098)	(18,331,272)
Cash and cash equivalents at beginning of period	88,067,647	106,398,919
Cash and cash equivalents at end of period	34,645,549	88,067,647
Cash paid for:
Interest	$ 1,051,167	$ 1,635,562