Fair Value Measurements and Financial Instruments - Narrative (Details) $ in Millions	3 Months Ended		12 Months Ended
	Mar. 31, 2024 USD ($)	Mar. 31, 2023 USD ($)	Dec. 31, 2023
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Gain (loss) on equity securities still held	$ 77.7	$ (10.8)
Cytokinetics Commercial Launch Funding | Level 3 | Measurement Input, Option Volatility
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Measurement input	0.375		0.375
Cytokinetics Commercial Launch Funding | Level 3 | Measurement Input, Discount Rate | Minimum
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Measurement input	0.117
Cytokinetics Commercial Launch Funding | Level 3 | Measurement Input, Discount Rate | Maximum
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Measurement input			0.109
Financial Royalty Assets, Current
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Financial royalty asset, percentage of non-controlling interest	13.20%		10.10%
Financial Royalty Assets, Non-current
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Financial royalty asset, percentage of non-controlling interest	9.20%		9.40%