Condensed Consolidated Statements of Convertible Preferred Stock and Stockholders' Equity (Deficit) - USD ($)	Total	Common Stock	Additional Paid-in Capital	Accumulated Deficit	Series A Convertible Preferred Stock	Series B Convertible Preferred Stock	Series B-1 Convertible Preferred Stock	Series C Convertible Preferred Stock	Series D Convertible Preferred Stock	Series D-1 Convertible Preferred Stock
Convertible Preferred Stock, Beginning Balance (shares) at Dec. 31, 2017					345,587	8,058,170	3,437,950	23,357,047	20,652,486	66,141,257
Convertible Preferred Stock, Beginning Balance at Dec. 31, 2017					$ 61,847	$ 842,845	$ 359,593	$ 5,547,841	$ 4,838,379	$ 31,359,632
Convertible Preferred Stock, Ending Balance (shares) at Mar. 31, 2018					345,587	8,058,170	3,437,950	23,357,047	20,652,486	66,141,257
Convertible Preferred Stock, Ending Balance at Mar. 31, 2018					$ 61,847	$ 842,845	$ 359,593	$ 5,547,841	$ 4,838,379	$ 31,359,632
Beginning Balance (shares) at Dec. 31, 2017		77,257
Beginning Balance at Dec. 31, 2017	$ (50,227,211)	$ 8	$ 4,038,817	$ (54,266,036)
Equity
Stock option exercises (shares)		237
Stock option exercises	305		305
Stock-based compensation expense	54,444		54,444
Net loss	(3,847,362)			(3,847,362)
Ending Balance (shares) at Mar. 31, 2018		77,494
Ending Balance at Mar. 31, 2018	(54,019,824)	$ 8	4,093,566	(58,113,398)
Convertible Preferred Stock, Beginning Balance (shares) at Dec. 31, 2017					345,587	8,058,170	3,437,950	23,357,047	20,652,486	66,141,257
Convertible Preferred Stock, Beginning Balance at Dec. 31, 2017					$ 61,847	$ 842,845	$ 359,593	$ 5,547,841	$ 4,838,379	$ 31,359,632
Convertible Preferred Stock, Ending Balance (shares) at Jun. 30, 2018					345,587	8,058,170	3,437,950	23,357,047	20,652,486	66,141,257
Convertible Preferred Stock, Ending Balance at Jun. 30, 2018					$ 61,847	$ 842,845	$ 359,593	$ 5,547,841	$ 4,838,379	$ 31,359,632
Beginning Balance (shares) at Dec. 31, 2017		77,257
Beginning Balance at Dec. 31, 2017	(50,227,211)	$ 8	4,038,817	(54,266,036)
Equity
Stock option exercises (shares)		788
Net loss	(7,158,838)
Ending Balance (shares) at Jun. 30, 2018		78,045
Ending Balance at Jun. 30, 2018	(57,277,611)	$ 8	4,147,255	(61,424,874)
Convertible Preferred Stock, Beginning Balance (shares) at Mar. 31, 2018					345,587	8,058,170	3,437,950	23,357,047	20,652,486	66,141,257
Convertible Preferred Stock, Beginning Balance at Mar. 31, 2018					$ 61,847	$ 842,845	$ 359,593	$ 5,547,841	$ 4,838,379	$ 31,359,632
Convertible Preferred Stock, Ending Balance (shares) at Jun. 30, 2018					345,587	8,058,170	3,437,950	23,357,047	20,652,486	66,141,257
Convertible Preferred Stock, Ending Balance at Jun. 30, 2018					$ 61,847	$ 842,845	$ 359,593	$ 5,547,841	$ 4,838,379	$ 31,359,632
Beginning Balance (shares) at Mar. 31, 2018		77,494
Beginning Balance at Mar. 31, 2018	(54,019,824)	$ 8	4,093,566	(58,113,398)
Equity
Stock option exercises (shares)		551
Stock option exercises	707		707
Stock-based compensation expense	52,982		52,982
Net loss	(3,311,476)			(3,311,476)
Ending Balance (shares) at Jun. 30, 2018		78,045
Ending Balance at Jun. 30, 2018	(57,277,611)	$ 8	4,147,255	(61,424,874)
Beginning Balance (shares) at Dec. 31, 2018		10,055,072
Beginning Balance at Dec. 31, 2018	10,137,351	$ 1,004	82,898,775	(72,762,428)
Equity
Stock option exercises (shares)		41,521
Stock option exercises	53,976	$ 4	53,972
Issue common stock (shares)		748,427
Issue common stock	2,409,593	$ 75	2,409,518
Stock-based compensation expense	289,395		289,395
Issue warrants for debt	629,830		629,830
Issue stock for debt	201,789		201,789
Net loss	(7,851,743)			(7,851,743)
Ending Balance (shares) at Mar. 31, 2019		10,845,020
Ending Balance at Mar. 31, 2019	5,870,191	$ 1,083	86,483,279	(80,614,171)
Beginning Balance (shares) at Dec. 31, 2018		10,055,072
Beginning Balance at Dec. 31, 2018	$ 10,137,351	$ 1,004	82,898,775	(72,762,428)
Equity
Stock option exercises (shares)		50,047
ESPP Purchases (shares)	66,155
Net loss	$ (15,516,309)
Ending Balance (shares) at Jun. 30, 2019		10,897,522
Ending Balance at Jun. 30, 2019	(1,344,810)	$ 1,088	86,932,839	(88,278,737)
Beginning Balance (shares) at Mar. 31, 2019		10,845,020
Beginning Balance at Mar. 31, 2019	5,870,191	$ 1,083	86,483,279	(80,614,171)
Equity
Stock option exercises (shares)		8,526
Stock option exercises	11,084	$ 1	11,083
Stock-based compensation expense	335,666		335,666
ESPP Purchases (shares)		43,976
ESPP Purchases	102,815	$ 4	102,811
Net loss	(7,664,566)
Ending Balance (shares) at Jun. 30, 2019		10,897,522
Ending Balance at Jun. 30, 2019	$ (1,344,810)	$ 1,088	$ 86,932,839	$ (88,278,737)