Statements of Cash Flows - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Cash flows from operating activities:
Net loss	$ (28,078,646)	$ (12,201,386)	$ (6,883,080)
Adjustments to reconcile net loss to net cash used in operating activities:
Stock-based compensation expense	2,899,304	1,297,985	260,361
Warrant remeasurement	1,879,823	(582,360)	854,336
Depreciation expense	53,116	31,229	4,444
Amortization of debt discount	104,311	35,288	0
Amortization of debt issuance costs	94,648	0	0
Non-cash interest expense	38,521	6,384	0
Changes in assets and liabilities:
Other receivable	0	459,018	(459,018)
Prepaid expenses and other assets	(814,156)	(96,754)	(261,332)
Accounts payable	(71,751)	526,869	(1,661,421)
Accrued expenses	2,142,187	808,514	100,817
Net cash used in operating activities	(21,752,643)	(9,715,213)	(8,044,893)
Cash flows from investing activities:
Purchases of property and equipment	(1,305,086)	(884,793)	(136,894)
Net cash used in investing activities	(1,305,086)	(884,793)	(136,894)
Cash flows from financing activities:
Proceeds from convertible note payable	0	0	100,000
Proceeds from issuance of debt	3,000,000	3,000,000	0
Proceeds from exercise of stock options	1,094	0	0
Payments for issuance costs	(1,402,845)	(1,351,450)	0
Payments for debt issuance costs	0	(94,998)	0
Payments for debt payable	(533,729)	0	0
Payments on note payable to stockholders	0	0	(22,052)
Proceeds from issuance of common stock, net of underwriting costs	86,059,087	0	0
Proceeds from issuance of preferred stock, net of issuance costs	52,394,571	14,917,257	15,821,075
Net cash provided by financing activities	139,518,178	16,470,809	15,899,023
Net increase in cash	116,460,449	5,870,803	7,717,236
Cash and cash equivalents at beginning of period	13,728,972	7,858,169
Cash and cash equivalents at end of period	130,189,421	13,728,972	7,858,169
Cash paid for:
Interest	559,175	82,729	94
Income taxes	0	0	1,759
Supplemental cash flow information:
Conversion of Preferred Stock to Common Stock	93,364,275	0	0
Conversion of Preferred Stock Warrants to Common Stock Warrants	3,726,043	0	0
Conversion of notes payable and accrued interest to preferred stock	0	0	253,365
Deferred issuance costs included in accrued expenses and accounts payable	549,178	53,946	0
Non-cash financing costs	175,114	0	0
Accrued capital expenditures included in accrued expenses	$ 71,040	$ 450,373	$ 0