CONDENSED CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Common stock	Additional paid-in capital	Accumulated deficit	Accumulated other comprehensive income (loss)
Balance at Dec. 31, 2018	$ 92,182	$ 10	$ 307,624	$ (215,409)	$ (43)
Balance (shares) at Dec. 31, 2018		97,864,663
CHANGES DURING THE PERIOD:
Comprehensive (loss) income	(57,314)			(57,358)	44
Exercise of options and vesting of restricted stock units	44		44
Exercise of options, vesting of restricted stock units and shares issued under employee stock purchase plan (in shares)		410,339
Stock-based compensation	3,606		3,606
Issuance of Ordinary Shares through a public offering, net of $3,903 issuance costs	15,011	$ 1	15,010
Issuance of Ordinary Shares through public offering, net of $3,903 issuance costs (in shares)		11,779,628
Balance at Sep. 30, 2019	53,529	$ 11	326,284	(272,767)	1
Balance (shares) at Sep. 30, 2019		110,054,630
CHANGES DURING THE PERIOD:
Payments of stock issuance costs	359
Balance at Jun. 30, 2019	60,382	$ 10	309,979	(249,606)	(1)
Balance (shares) at Jun. 30, 2019		98,053,418
CHANGES DURING THE PERIOD:
Comprehensive (loss) income	(23,159)			(23,161)	2
Exercise of options and vesting of restricted stock units	26		26
Exercise of options, vesting of restricted stock units and shares issued under employee stock purchase plan (in shares)		221,584
Stock-based compensation	1,269		1,269
Issuance of Ordinary Shares through a public offering, net of $3,903 issuance costs	15,011	$ 1	15,010
Issuance of Ordinary Shares through public offering, net of $3,903 issuance costs (in shares)		11,779,628
Balance at Sep. 30, 2019	53,529	$ 11	326,284	(272,767)	1
Balance (shares) at Sep. 30, 2019		110,054,630
CHANGES DURING THE PERIOD:
Payments of stock issuance costs	359
Balance at Dec. 31, 2019	$ 17,575	$ 3	328,154	(310,587)	5
Balance (shares) at Dec. 31, 2019	36,480,314	36,480,314
CHANGES DURING THE PERIOD:
Comprehensive (loss) income	$ (232,392)			(232,387)	(5)
Exercise of options and vesting of restricted stock units	342		342
Exercise of options, vesting of restricted stock units and shares issued under employee stock purchase plan (in shares)		1,207,650
Stock-based compensation	15,147		15,147
Deemed dividend to warrants holders due to warrant modification	0		41	(41)
Classification of stock awards to derivative liability	(975)		(975)
Issuance of Ordinary Shares through a public offering, net of $3,903 issuance costs	53,649	$ 3	53,646
Issuance of Ordinary Shares through public offering, net of $3,903 issuance costs (in shares)		31,107,500
Issuance of stock related to merger	196,170	$ 11	196,159
Issuance of stock related to merger (in shares)		99,063,997
Balance at Sep. 30, 2020	$ 49,516	$ 17	592,514	(543,015)	0
Balance (shares) at Sep. 30, 2020	167,859,461	167,859,461
CHANGES DURING THE PERIOD:
Payments of stock issuance costs	$ 3,903
Balance at Jun. 30, 2020	71,528	$ 17	589,812	(518,301)	0
Balance (shares) at Jun. 30, 2020		167,683,814
CHANGES DURING THE PERIOD:
Comprehensive (loss) income	(24,714)			(24,714)	0
Exercise of options and vesting of restricted stock units	82		82
Exercise of options, vesting of restricted stock units and shares issued under employee stock purchase plan (in shares)		175,647
Stock-based compensation	2,620		2,620
Balance at Sep. 30, 2020	$ 49,516	$ 17	$ 592,514	$ (543,015)	$ 0
Balance (shares) at Sep. 30, 2020	167,859,461	167,859,461