Fair Value Measurements - Additional Information (Details) $ in Millions	3 Months Ended		12 Months Ended
	Mar. 30, 2019 USD ($)	Mar. 31, 2018 USD ($)	Dec. 31, 2020 USD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Transfers among level 1, 2, and 3	$ 0.0	$ 0.0
Fair value adjustment		250.0
Income recognized from change is asset	10.4	(9.6)
Measured on a recurring basis | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Potential contingent milestone payments	83.6			$ 323.2
Royalty Pharma Contingent Milestone Payments | Measured on a recurring basis | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Increase (decrease) in fair value of milestone payment	10.4	(9.6)
Estimated fair valued contingent milestone payment	$ 83.6	$ 124.9		$ 323.2	$ 134.5
Royalty Pharma
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Rate of return	8.02%	8.08%
Measurement Input, Price Volatility | Royalty Pharma
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Volatility rate assumed	0.300	0.300
Measurement Input, Long-term Revenue Growth Rate | CSCA
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Reporting Unit, Discounted Cash Flow, Measurement Input				0.025
Indefinite-lived Intangible Assets (Excluding Goodwill), Measurement Input				(0.003)
Measurement Input, Discount Rate | CSCA
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Reporting Unit, Discounted Cash Flow, Measurement Input				0.098
Indefinite-lived Intangible Assets (Excluding Goodwill), Measurement Input				0.098
Measurement Input, Tax Rate | CSCA
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Reporting Unit, Discounted Cash Flow, Measurement Input				0.228
Indefinite-lived Intangible Assets (Excluding Goodwill), Measurement Input				0.228
Scenario, Forecast
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Adjusted asset balance is prescribed threshold is exceeded			$ 400.0
Scenario, Forecast | Royalty Pharma Contingent Milestone Payments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Net sales threshold to trigger milestone payment			351.0
Write-off of contingent milestone payment if sales threshold is not met			83.6
Adjusted asset balance is prescribed threshold is exceeded			400.0
Income recognized from change is asset			$ 316.4