CONDENSED CONSOLIDATED STATEMENTS OF CONVERTIBLE PREFERRED STOCK, REDEEMABLE COMMON STOCK AND STOCKHOLDERS' EQUITY (DEFICIT) - USD ($) $ in Thousands	Total	Series Seed, A and B Convertible Preferred	Redeemable Common Stock	Common Stock	Additional Paid-In Capital	Accumulated Other Comprehensive Loss	Accumulated Deficit
Convertible preferred shares, beginning balance, shares at Dec. 31, 2018		40,079,567
Convertible preferred shares, beginning balance at Dec. 31, 2018		$ 64,675
Increase (Decrease) in Temporary Equity [Roll Forward]
Conversion of convertible preferred shares into common stock, shares		(40,079,567)		3,808,430
Conversion of convertible preferred shares into common stock	$ 64,675	$ (64,675)		$ 4	$ 64,671
Convertible preferred shares, ending balance, shares at Mar. 31, 2019		0
Convertible preferred shares, ending balance at Mar. 31, 2019		$ 0
Beginning balance, shares at Dec. 31, 2018			107,364	351,652
Beginning balance at Dec. 31, 2018	(77,086)		$ 734	$ 0	2,151	$ 0	$ (79,237)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Conversion of redeemable common stock into common stock, shares			107,364	107,364
Conversion of redeemable common stock into common stock	734		$ (734)	$ 1	733
Exchange of common stock in connection with Merger, shares				2,440,582
Exchange of common stock in connection with Merger	45,541			$ 2	45,539
Fair value of replacement equity awards	817				817
Reclassification of warrant liability to permanent equity	5,235				5,235
Exercise of stock options, shares				16,483
Exercise of stock options	113				113
Stock-based compensation expense	262				262
Currency translation adjustments	23					23
Net loss	(10,873)						(10,873)
Ending balance, shares at Mar. 31, 2019			0	6,724,511
Ending balance at Mar. 31, 2019	29,441		$ 0	$ 7	119,521	23	(90,110)
Beginning balance, shares at Dec. 31, 2019				16,128,862
Beginning balance at Dec. 31, 2019	129,220			$ 16	261,367	(119)	(132,044)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Conversion of redeemable common stock into common stock	$ 0
Exercise of stock options, shares	13,006			13,006
Exercise of stock options	$ 96				96
Stock-based compensation expense	613				613
Net loss	(11,138)						(11,138)
Ending balance, shares at Mar. 31, 2020				16,141,868
Ending balance at Mar. 31, 2020	$ 118,791			$ 16	$ 262,076	$ (119)	$ (143,182)