Investments in Variable Interest Entities (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022
Variable Interest Entity [Line Items]
(Gain) loss on equity method investments		$ 0.0	$ 2.6
Percentage of future development costs related to Eisai		45.00%
Deferred tax assets, unrecognized tax benefit		$ 85.0
Investment in biotechnology companies that are determined to be unconsolidated variable interest entities		$ 24.4		$ 27.8
Neurimmune
Variable Interest Entity [Line Items]
Collaboration agreement term		12 years
Research and development costs, percentage		100.00%
Eisai
Variable Interest Entity [Line Items]
Percentage of future development costs related to Eisai	45.00%