Consolidated Statements of Redeemable Convertible Preferred Stock and Stockholders’ Equity (Deficit) - USD ($) $ in Thousands	Series A Redeemable convertible preferred stock Preferred Stock [Member]	Series B Redeemable convertible preferred stock Preferred Stock [Member]	Common stock	Additional paid-in capital	Accumulated other comprehensive income	Accumulated deficit	Total
Balance at Beginning of period at Dec. 31, 2018	$ 33,112	$ 91,038
Balance at Beginning of period (in shares) at Dec. 31, 2018	22,501,174	63,032,500
Increase (Decrease) in Temporary Equity [Roll Forward]
Sale of Series B redeemable convertible preferred stock, net of stock issue costs		10,554,514
Sale of Series B redeemable convertible preferred stock, net of stock issue costs		$ 12,126
Accretion of redeemable convertible preferred stock to redemption value	$ 893	3,894
Balance at Ending period at Jun. 30, 2019	$ 34,005	$ 107,058
Balance at Ending period (in shares) at Jun. 30, 2019	22,501,174	73,587,014
Balance at Beginning of period at Dec. 31, 2018						$ (137,860)	$ (137,860)
Balance at Beginning of period (in shares) at Dec. 31, 2018			295,717
Increase (Decrease) in Temporary Equity [Roll Forward]
Vesting of common stock previously subject to repurchase (in shares)			295
Vesting of common stock previously subject to repurchase				$ 3			3
Exercise of stock options (in shares)			1,490
Exercise of stock options				8			8
Foreign currency translation adjustment					$ (3)		(3)
Stock-based compensation expense				119			119
Accretion of redeemable convertible preferred stock to redemption value				(130)		(4,657)	(4,787)
Net loss						(11,227)	(11,227)
Balance at Ending period at Jun. 30, 2019					(3)	(153,744)	(153,747)
Balance at Ending period (in shares) at Jun. 30, 2019			297,502
Balance at Beginning of period at Mar. 31, 2019	$ 33,556	$ 93,100
Balance at Beginning of period (in shares) at Mar. 31, 2019	22,501,174	63,463,534
Increase (Decrease) in Temporary Equity [Roll Forward]
Sale of Series B redeemable convertible preferred stock, net of stock issue costs		10,123,480
Sale of Series B redeemable convertible preferred stock, net of stock issue costs		$ 11,645
Accretion of redeemable convertible preferred stock to redemption value	$ 449	2,313
Balance at Ending period at Jun. 30, 2019	$ 34,005	$ 107,058
Balance at Ending period (in shares) at Jun. 30, 2019	22,501,174	73,587,014
Balance at Beginning of period at Mar. 31, 2019					(4)	(145,788)	(145,792)
Balance at Beginning of period (in shares) at Mar. 31, 2019			296,245
Increase (Decrease) in Temporary Equity [Roll Forward]
Vesting of common stock previously subject to repurchase (in shares)			165
Vesting of common stock previously subject to repurchase				3			3
Exercise of stock options (in shares)			1,092
Exercise of stock options				5			5
Foreign currency translation adjustment					1		1
Stock-based compensation expense				59			59
Accretion of redeemable convertible preferred stock to redemption value				(67)		(2,695)	(2,762)
Net loss						(5,261)	(5,261)
Balance at Ending period at Jun. 30, 2019					(3)	(153,744)	(153,747)
Balance at Ending period (in shares) at Jun. 30, 2019			297,502
Balance at Beginning of period at Dec. 31, 2019			$ 11	198,829	(19)	(167,859)	30,962
Balance at Beginning of period (in shares) at Dec. 31, 2019			11,406,221
Increase (Decrease) in Temporary Equity [Roll Forward]
Vesting of common stock previously subject to repurchase (in shares)			163
Vesting of common stock previously subject to repurchase				2			$ 2
Exercise of stock options (in shares)			6,306				6,306
Exercise of stock options				44			$ 44
Issuance of stock			$ 3	44,719			44,722
Issuance of stock (in shares)			3,000,000
Foreign currency translation adjustment					31		31
Stock-based compensation expense				943			943
Net loss						(13,301)	(13,301)
Balance at Ending period at Jun. 30, 2020			$ 14	244,537	12	(181,160)	63,403
Balance at Ending period (in shares) at Jun. 30, 2020			14,412,690
Balance at Beginning of period at Mar. 31, 2020			$ 11	199,287	8	(175,079)	24,227
Balance at Beginning of period (in shares) at Mar. 31, 2020			11,407,600
Increase (Decrease) in Temporary Equity [Roll Forward]
Vesting of common stock previously subject to repurchase (in shares)			73
Vesting of common stock previously subject to repurchase				1			1
Exercise of stock options (in shares)			5,017
Exercise of stock options				36			36
Issuance of stock			$ 3	44,719			44,722
Issuance of stock (in shares)			3,000,000
Foreign currency translation adjustment					4		4
Stock-based compensation expense				494			494
Net loss						(6,081)	(6,081)
Balance at Ending period at Jun. 30, 2020			$ 14	$ 244,537	$ 12	$ (181,160)	$ 63,403
Balance at Ending period (in shares) at Jun. 30, 2020			14,412,690