CONDENSED CONSOLIDATED STATEMENTS OF REDEEMABLE CONVERTIBLE PREFERRED STOCK AND STOCKHOLDERS’ EQUITY (DEFICIT) - USD ($) $ in Thousands	Total	Series A, B, C & C-1 Redeemable Convertible Preferred Stock	Common Stock	Additional Paid-In Capital	Accumulated Other Comprehensive Loss	Accumulated Deficit	Redeemable Convertible Preferred Stock and Preferred Stock Dividends to Common Stock	Redeemable Convertible Preferred Stock and Preferred Stock Dividends to Common Stock Series A, B, C & C-1 Redeemable Convertible Preferred Stock	Redeemable Convertible Preferred Stock and Preferred Stock Dividends to Common Stock Common Stock	Redeemable Convertible Preferred Stock and Preferred Stock Dividends to Common Stock Additional Paid-In Capital	Convertible Notes Payable and Accrued Interest to Common Stock	Convertible Notes Payable and Accrued Interest to Common Stock Common Stock	Convertible Notes Payable and Accrued Interest to Common Stock Additional Paid-In Capital
Beginning Balance (in shares) at Dec. 31, 2017			585,262
Beginning Balance at Dec. 31, 2017	$ (59,936)		$ 6	$ 0	$ 0	$ (59,942)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock based compensation	711			711
Issuance of common stock through exercise of stock option (in shares)			3,739
Issuance of common stock through exercise of stock option	45			45
Accretion of redeemable convertible preferred stock to redemption value	(5,936)			(756)		(5,180)
Net income (loss)	(9,236)					(9,236)
Unrealized loss on available-for-sale marketable securities	$ 0
Ending Balance (in shares) at Dec. 31, 2018	589,001		589,001
Ending Balance at Dec. 31, 2018	$ (71,618)		$ 6	0	0	(71,624)
Beginning Balance (in shares) at Dec. 31, 2017		1,256,466
Beginning Balance at Dec. 31, 2017		$ 52,354
Increase (Decrease) in Temporary Equity [Roll Forward]
Accretion of redeemable convertible preferred stock to redemption value		$ 5,936
Shares converted	$ 0
Ending Balance (in shares) at Dec. 31, 2018	1,256,466	1,256,466
Ending Balance at Dec. 31, 2018	$ 58,290	$ 58,290
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock based compensation	$ 1,532			1,532
Issuance of common stock through exercise of stock option (in shares)	0		670,288
Issuance of common stock through exercise of stock option	$ 47		$ 7	40
Accretion of redeemable convertible preferred stock to redemption value	10,274			(247)		10,521
Net income (loss)	(23,877)					(23,877)
Conversion of securities (in shares)									2,783,951			1,069,740
Conversion of securities							$ 48,016		$ 28	$ 47,988	$ 5,092	$ 10	$ 5,082
Common stock issued in recapitalization (in shares)			3,367,988
Common stock issued in recapitalization	36,093		$ 34	36,059
Reclassification of warrant liability to equity	1,511			1,511
Common stock warrants issued in connection with the research and development funding liability, net of cancellations	532			532
Unrealized loss on available-for-sale marketable securities	$ (28)				(28)
Ending Balance (in shares) at Dec. 31, 2019	8,480,968		8,480,968
Ending Balance at Dec. 31, 2019	$ 7,574		$ 85	$ 92,497	$ (28)	$ (84,980)
Increase (Decrease) in Temporary Equity [Roll Forward]
Accretion of redeemable convertible preferred stock to redemption value		$ (10,274)
Shares converted (in shares)								(1,256,466)
Shares converted	$ (48,016)							$ (48,016)
Ending Balance (in shares) at Dec. 31, 2019	0	0
Ending Balance at Dec. 31, 2019	$ 0	$ 0