Statements of Changes in Shareholders' Equity - USD ($) $ in Thousands	Total	Cumulative Effect, Period of Adoption, Adjustment	Ordinary shares	Additional paid-in capital	Accumulated other comprehensive income (loss)	Retained earnings (accumulated deficit)	Retained earnings (accumulated deficit) Cumulative Effect, Period of Adoption, Adjustment
Beginning balance at Dec. 31, 2017	$ 113,564	$ 2,162		$ 697,165	$ (1,343)	$ (582,258)	$ 2,162
Beginning balance (in shares) at Dec. 31, 2017			89,478,032
Share-based compensation to employees	39,846			39,846
Exercise of options and warrants	18,468			18,468
Exercise of options and warrants (in shares)			3,688,781
Issuance of shares in connection with employee stock purchase plan	1,835			1,835
Issuance of shares in connection with employee stock purchase plan (in shares)			87,372
Other comprehensive income (loss), net of tax (benefit) expense	(57)				(57)
Net income (loss)	(63,559)					(63,559)
Ending balance at Dec. 31, 2018	112,259			757,314	(1,400)	(643,655)
Ending balance (in shares) at Dec. 31, 2018			93,254,185
Share-based compensation to employees	52,416			52,416
Exercise of options	59,245			59,245
Exercise of options (in shares)			6,206,884
Issuance of shares in connection with employee stock purchase plan	2,467			2,467
Issuance of shares in connection with employee stock purchase plan (in shares)			67,366
Other comprehensive income (loss), net of tax (benefit) expense	(1,367)				(1,367)
Net income (loss)	(7,230)					(7,230)
Ending balance at Dec. 31, 2019	217,790			871,442	(2,767)	(650,885)
Ending balance (in shares) at Dec. 31, 2019			99,528,435
Share-based compensation to employees	75,721			75,721
Exercise of options	$ 28,428			28,428
Exercise of options (in shares)	1,816,851		2,739,150
Issuance of shares in connection with employee stock purchase plan	$ 3,370			3,370
Issuance of shares in connection with employee stock purchase plan (in shares)			66,691
Conversion feature of convertible note, net	132,474			132,474
Other comprehensive income (loss), net of tax (benefit) expense	(1,065)				(1,065)
Net income (loss)	19,808					19,808
Ending balance at Dec. 31, 2020	$ 476,526			$ 1,111,435	$ (3,832)	$ (631,077)
Ending balance (in shares) at Dec. 31, 2020			102,334,276