Condensed Consolidated Statements of Stockholders' Equity (Unaudited) - USD ($) $ in Thousands	Total	Series C Preferred Stock	Series C-1 Preferred Stock	Common Stock	Common Stock Series C Preferred Stock	Common Stock Series C-1 Preferred Stock	Common Stock Series B Preferred Stock	Common Stock March 20, 2019	Common Stock May 17, 2019	Common Stock August 2019	Common Stock June Twelve Two Thousand Nineteen	Additional Paid-in Capital	Additional Paid-in Capital Series C Preferred Stock	Additional Paid-in Capital Series C-1 Preferred Stock	Accumulated Deficit	Accumulated Other Comprehensive Income/(Loss)
Beginning balance at Dec. 31, 2017	$ 8,154			$ 1								$ 47,393			$ (39,197)	$ (43)
Beginning balance, shares at Dec. 31, 2017				8,575,950
Net loss	(23,233)														(23,233)
Issuance of preferred stock upon conversion of common stock		$ 20,972	$ 6,417										$ 20,972	$ 6,417
Issuance of preferred stock upon conversion of common stock, shares					1,536,602	491,260
Issuance of common stock, shares				897,435			28,478
Stock-based compensation	482											482
Exercise of stock options	18											18
Exercise of stock options, shares				4,465
Other comprehensive income (loss)	57															57
Ending balance at Sep. 30, 2018	12,867			$ 1								75,282			(62,430)	14
Ending balance, shares at Sep. 30, 2018				11,534,190
Beginning balance at Jun. 30, 2018	11,472			$ 1								68,741			(57,303)	33
Beginning balance, shares at Jun. 30, 2018				10,117,017
Net loss	(5,127)														(5,127)
Issuance of preferred stock upon conversion of common stock		$ (17)	$ 6,417										$ (17)	$ 6,417
Issuance of preferred stock upon conversion of common stock, shares						491,260
Issuance of common stock, shares				897,435			28,478
Stock-based compensation	141											141
Other comprehensive income (loss)	(19)															(19)
Ending balance at Sep. 30, 2018	12,867			$ 1								75,282			(62,430)	14
Ending balance, shares at Sep. 30, 2018				11,534,190
Beginning balance at Dec. 31, 2018	5,369			$ 1								76,348			(71,020)	40
Beginning balance, shares at Dec. 31, 2018				11,534,190
Net loss	(40,243)														(40,243)
Issuance of restricted common stock, shares								2,406,618	19,407	84,975	64,982
Issuance of common stock	29,607			$ 1								29,606
Issuance of common stock, shares				3,600,000
Stock-based compensation	24,747											24,747
Exercise of stock options	$ 2											2
Exercise of stock options, shares	487			487
Other comprehensive income (loss)	$ 26															26
Ending balance at Sep. 30, 2019	19,508			$ 2								130,703			(111,263)	66
Ending balance, shares at Sep. 30, 2019				17,710,659
Beginning balance at Jun. 30, 2019	23,115			$ 2								119,348			(96,288)	53
Beginning balance, shares at Jun. 30, 2019				17,625,241
Net loss	(14,975)														(14,975)
Issuance costs from Initial Public Offering	(21)											(21)
Issuance of restricted common stock, shares										84,975
Stock-based compensation	11,374											11,374
Exercise of stock options	2											2
Exercise of stock options, shares				443
Other comprehensive income (loss)	13															13
Ending balance at Sep. 30, 2019	$ 19,508			$ 2								$ 130,703			$ (111,263)	$ 66
Ending balance, shares at Sep. 30, 2019				17,710,659