Revenues - Schedule of Disaggregation of Revenue (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2026	Mar. 31, 2025
Disaggregation of Revenue [Line Items]
Total revenues	$ 1,068.9	$ 897.8
U.S.
Disaggregation of Revenue [Line Items]
Total revenues	959.8	797.9
Europe
Disaggregation of Revenue [Line Items]
Total revenues	92.4	83.6
All other
Disaggregation of Revenue [Line Items]
Total revenues	16.7	16.3
Product sales, net
Disaggregation of Revenue [Line Items]
Total revenues	1,025.3	839.4
Sleep
Disaggregation of Revenue [Line Items]
Total revenues	439.4	382.0
Xywav
Disaggregation of Revenue [Line Items]
Total revenues	408.2	344.8
Xyrem
Disaggregation of Revenue [Line Items]
Total revenues	31.2	37.2
Epilepsy
Disaggregation of Revenue [Line Items]
Total revenues	249.8	217.7
Epidiolex/Epidyolex
Disaggregation of Revenue [Line Items]
Total revenues	249.8	217.7
Oncology
Disaggregation of Revenue [Line Items]
Total revenues	333.4	229.4
Rylaze/Enrylaze
Disaggregation of Revenue [Line Items]
Total revenues	103.7	94.2
Zepzelca
Disaggregation of Revenue [Line Items]
Total revenues	101.0	63.0
Defitelio/defibrotide
Disaggregation of Revenue [Line Items]
Total revenues	47.4	40.7
Modeyso
Disaggregation of Revenue [Line Items]
Total revenues	41.4	0.0
Vyxeos
Disaggregation of Revenue [Line Items]
Total revenues	26.6	29.5
Ziihera
Disaggregation of Revenue [Line Items]
Total revenues	13.3	2.0
Other
Disaggregation of Revenue [Line Items]
Total revenues	2.7	10.3
High-sodium oxybate AG royalty revenue
Disaggregation of Revenue [Line Items]
Total revenues	36.3	48.9
Other royalty and contract revenues
Disaggregation of Revenue [Line Items]
Total revenues	$ 7.3	$ 9.5