Statements of Changes in Shareholders' Equity - USD ($) $ in Thousands	Total	Ordinary Shares	Additional Paid-in Capital	Accumulated Other Comprehensive Income (Loss)	Retained Earnings (Accumulated Deficit)
Balance at Dec. 31, 2015	$ 250,820		$ 640,406	$ (1,505)	$ (388,081)
Balance (in shares) at Dec. 31, 2015		83,778,581
Share-based compensation to employees	21,441		21,441
Exercise of options and warrants	993		993
Exercise of options and warrants (in shares)		3,195,477
Issuance of shares in connection with employee stock purchase plan	616		616
Issuance of shares in connection with employee stock purchase plan(in shares)		92,388
Tax benefit from share-based award activity	698		698
Other comprehensive income (loss), net of tax (benefit) expense of $38, $68, and $10 for the years ended December 2016, 2017 and 2018	(378)			(378)
Net income (loss)	(131,845)				(131,845)
Balance at Dec. 31, 2016	142,345		664,154	(1,883)	(519,926)
Balance (in shares) at Dec. 31, 2016		87,066,446
Cumulative effect adjustment resulting from ASU 2016-09 adoption (See Note 2)			670		(670)
Share-based compensation to employees	27,116		27,116
Exercise of options and warrants	3,685		3,685
Exercise of options and warrants (in shares)		2,244,153
Issuance of shares in connection with employee stock purchase plan	1,540		1,540
Issuance of shares in connection with employee stock purchase plan(in shares)		167,433
Other comprehensive income (loss), net of tax (benefit) expense of $38, $68, and $10 for the years ended December 2016, 2017 and 2018	540			540
Net income (loss)	(61,662)				(61,662)
Balance at Dec. 31, 2017	113,564		697,165	(1,343)	(582,258)
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
Proceeds from issuance of shares	1,835		1,835
Proceeds from issuance of shares (in shares)		87,372
Cumulative effect adjustment resulting from ASC 606 adoption (See note 2)	2,162				2,162
Other comprehensive income (loss), net of tax (benefit) expense of $38, $68, and $10 for the years ended December 2016, 2017 and 2018	(57)			(57)
Net income (loss)	(63,559)				(63,559)
Balance at Dec. 31, 2018	$ 112,259		$ 757,314	$ (1,400)	$ (643,655)
Balance (in shares) at Dec. 31, 2018		93,254,185