CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Ordinary Shares	Additional Paid-In Capital	Accumulated Other Comprehensive Loss	Accumulated Deficit	Treasury Stock
BALANCE at Dec. 31, 2020	$ 1,066,982	$ 1,620	$ 2,685,647	$ (1,349)	$ (1,492,849)	$ (126,087)
BALANCE (in shares) at Dec. 31, 2020		162,269,220				(3,108,079)
Issuance of ordinary shares under employee stock plans	25,319	$ 38	25,281
Issuance of ordinary shares under employee stock plans (in shares)		3,521,329
Receipt of Alkermes' shares for the exercise of stock options or to satisfy minimum tax withholding obligations related to share-based awards	(16,571)					$ (16,571)
Receipt of Alkermes' shares for the exercise of stock options or to satisfy minimum tax withholding obligations related to share-based awards (in shares)						(745,143)
Share-based compensation	87,397		87,397
Unrealized gain (loss) on marketable securities, net of tax provision (benefit)	(2,374)			(2,374)
Net Income (Loss)	(48,169)				(48,169)
BALANCE at Dec. 31, 2021	1,112,584	$ 1,658	2,798,325	(3,723)	(1,541,018)	$ (142,658)
BALANCE (in shares) at Dec. 31, 2021		165,790,549				(3,853,222)
Issuance of ordinary shares under employee stock plans	19,630	$ 32	19,598
Issuance of ordinary shares under employee stock plans (in shares)		3,160,644
Receipt of Alkermes' shares for the exercise of stock options or to satisfy minimum tax withholding obligations related to share-based awards	(18,204)					$ (18,204)
Receipt of Alkermes' shares for the exercise of stock options or to satisfy minimum tax withholding obligations related to share-based awards (in shares)						(720,962)
Share-based compensation	95,176		95,176
Unrealized gain (loss) on marketable securities, net of tax provision (benefit)	(7,166)			(7,166)
Net Income (Loss)	(158,267)				(158,267)
BALANCE at Dec. 31, 2022	1,043,753	$ 1,690	2,913,099	(10,889)	(1,699,285)	$ (160,862)
BALANCE (in shares) at Dec. 31, 2022		168,951,193				(4,574,184)
Issuance of ordinary shares under employee stock plans	16,760	$ 36	16,724
Issuance of ordinary shares under employee stock plans (in shares)		3,617,858
Receipt of Alkermes' shares for the exercise of stock options or to satisfy minimum tax withholding obligations related to share-based awards	(28,474)					$ (28,474)
Receipt of Alkermes' shares for the exercise of stock options or to satisfy minimum tax withholding obligations related to share-based awards (in shares)						(1,015,034)
Share-based compensation	100,871		100,871
Unrealized gain (loss) on marketable securities, net of tax provision (benefit)	7,779			7,779
Distribution of Mural Oncology plc	(293,760)		(293,760)
Net Income (Loss)	355,757				355,757
BALANCE at Dec. 31, 2023	$ 1,202,686	$ 1,726	$ 2,736,934	$ (3,110)	$ (1,343,528)	$ (189,336)
BALANCE (in shares) at Dec. 31, 2023		172,569,051				(5,589,218)