CONSOLIDATED STATEMENTS OF REDEEMABLE CONVERTIBLE PREFERRED STOCK AND STOCKHOLDERS’ DEFICIT - USD ($) $ in Thousands	Common Stock Common stock	Common Stock Class A common stock	Additional Paid-In Capital	Accumulated Other Comprehensive Income (Loss)	Accumulated Deficit	Convertible preferred stock	Series B Preferred Stock	Series C Preferred Stock	Series D Preferred Stock	Total
Balance at the beginning of the period at Dec. 31, 2016						$ 40,189
Balance at the beginning of the period (in shares) at Dec. 31, 2016						547,974
Increase (Decrease) in Temporary Equity
Issuance of preferred stock, net of issuance costs							$ 5,315	$ 59,270
Issuance of preferred stock, net of issuance costs (in shares)							82,032	693,500
Balance at the end of the period at Dec. 31, 2017						$ 104,774
Balance at the end of the period (in shares) at Dec. 31, 2017						1,323,506
Balance at the beginning of the period at Dec. 31, 2016			$ 1,682	$ (3,126)	$ (31,022)					$ (32,466)
Balance at the beginning of the period (in shares) at Dec. 31, 2016	911,777
Increase (Decrease) in Stockholders' Equity
Issuance of common stock upon exercise of stock options (in shares)										0
Foreign currency translation adjustment, net of tax				1,764						$ 1,764
Stock-based compensation expense			769							769
Net loss					(12,723)					(12,723)
Balance at the end of the period at Dec. 31, 2017			2,451	(1,362)	(43,745)					(42,656)
Balance at the end of the period (in shares) at Dec. 31, 2017	911,777
Balance at the end of the period at Dec. 31, 2018						$ 104,774				$ 104,774
Balance at the end of the period (in shares) at Dec. 31, 2018						1,323,506	492,192	693,500		1,323,506
Increase (Decrease) in Stockholders' Equity
Issuance of common stock upon exercise of stock options			9							$ 9
Issuance of common stock upon exercise of stock options (in shares)	94,818
Foreign currency translation adjustment, net of tax				(2,358)						(2,358)
Stock-based compensation expense			867							867
Net loss					(16,237)					(16,237)
Balance at the end of the period at Dec. 31, 2018			3,327	(3,720)	(59,982)					$ (60,375)
Balance at the end of the period (in shares) at Dec. 31, 2018	1,006,595
Balance at the end of the period (in shares) at Mar. 31, 2019							492,192	693,500	257,000	1,580,506
Increase (Decrease) in Stockholders' Equity
Net loss										$ (9,329)
Balance at the beginning of the period at Dec. 31, 2018						$ 104,774				$ 104,774
Balance at the beginning of the period (in shares) at Dec. 31, 2018						1,323,506	492,192	693,500		1,323,506
Increase (Decrease) in Temporary Equity
Issuance of preferred stock, net of issuance costs									$ 37,274
Issuance of preferred stock, net of issuance costs (in shares)									257,000
Conversion of Series A, B, C and D preferred stock into common stock upon initial public offering						$ (142,048)
Conversion of Series A, B, C and D preferred stock into common stock upon initial public offering(in shares)						(1,580,506)
Balance at the end of the period (in shares) at Dec. 31, 2019										0
Balance at the beginning of the period at Dec. 31, 2018			3,327	(3,720)	(59,982)					$ (60,375)
Balance at the beginning of the period (in shares) at Dec. 31, 2018	1,006,595
Increase (Decrease) in Stockholders' Equity
Issuance of common stock upon initial public offering at $14.00 per share for cash, net of issuance costs of $9,386	$ 1		74,614							74,615
Issuance of common stock upon initial public offering at $14.00 per share for cash, net of issuance costs of $9,386(in shares)	6,000,000
Conversion of Series A, B, C and D preferred stock into common stock upon initial public offering	$ 2		142,046							142,048
Conversion of Series A, B, C and D preferred stock into common stock upon initial public offering(in shares)	14,582,161	3,819,732
Issuance of common stock upon exercise of stock options			16							$ 16
Issuance of common stock upon exercise of stock options (in shares)	157,636									157,636
Foreign currency translation adjustment, net of tax				(933)						$ (933)
Stock-based compensation expense			5,565							5,565
Net loss					(43,037)					(43,037)
Balance at the end of the period at Dec. 31, 2019	$ 3		$ 225,568	$ (4,653)	$ (103,019)					$ 117,899
Balance at the end of the period (in shares) at Dec. 31, 2019	21,746,392	3,819,732