Condensed Consolidated Statements of Redeemable Convertible Preferred Stock and Stockholders' Equity (Deficit) - USD ($) $ in Thousands	Total	IPO	Redeemable Convertible Preferred Stock	Redeemable Convertible Preferred Stock IPO	Common Stock	Common Stock IPO	Additional Paid-in Capital	Accumulated Deficit	Accumulated Other Comprehensive Income	Non-controlling Interest
Temporary equity, beginning balance at Dec. 31, 2017			$ 105,235
Temporary equity, beginning balance (in shares) at Dec. 31, 2017			21,233,190
Temporary equity, ending balance at Dec. 31, 2018	$ 105,235		$ 105,235
Temporary equity, ending balance (in shares) at Dec. 31, 2018	21,233,190		21,233,190
Beginning balance (in shares) at Dec. 31, 2017					663,270
Beginning balance at Dec. 31, 2017	$ (98,578)				$ 1		$ 2,977	$ (101,556)	$ 0	$ 0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of stock options	$ 656						656
Exercise of stock options (in shares)	438,578				438,578
Employee stock-based compensation	$ 728						728
Nonemployee stock-based compensation	183						183
NeuroCo common stock issuance	1									1
Issuance of common stock in connection with NeuroCo merger (in shares)					33,462
Issuance of common stock in connection with NeuroCo merger	0
Net loss	(37,630)							(37,629)		(1)
Comprehensive loss	(37,630)							(37,629)		(1)
Unrealized gain on investments, net	0
Ending balance at Dec. 31, 2018	(134,553)				$ 1		4,557	(139,111)	0	0
Ending balance (in shares) at Dec. 31, 2018					1,135,310
Temporary Equity [Abstract]
Exercise of warrants	31	$ 0	$ 1,784	$ 37,121			31
Exercise of warrants (in shares)			292,361	1,653,004	3,764	2,204
Temporary equity, ending balance at Dec. 31, 2019	$ 0		$ 0
Temporary equity, ending balance (in shares) at Dec. 31, 2019	0		0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of stock options	$ 1,542				$ 1		1,541
Exercise of stock options (in shares)	873,786				873,786
Issuance of common stock in connection with IPO, net of underwriting discount, commissions and offering costs of $2,481	$ 109,119				$ 6		109,113
Issuance of common stock in connection with IPO, net of underwriting discount, commissions and offering costs (in shares)					6,000,000
Conversion of preferred stock to common stock upon IPO (in shares)			(23,178,555)		23,178,555
Conversion of preferred stock to common stock upon IPO	144,140		$ (144,140)		$ 23		144,117
Issuance of common stock under employee stock purchase plan	1,048						1,048
Issuance of common stock under employee stock purchase plan (in shares)					61,648
Employee stock-based compensation	2,887						2,887
Nonemployee stock-based compensation	90						90
Net loss	(52,415)							(52,415)
Unrealized gain on investments, net	2								2
Ending balance at Dec. 31, 2019	$ 71,891				$ 31		$ 263,384	$ (191,526)	$ 2	$ 0
Ending balance (in shares) at Dec. 31, 2019					31,255,267