Fair Value Measurements - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended			9 Months Ended		12 Months Ended
	Sep. 26, 2020	Sep. 28, 2019	Mar. 30, 2019	Sep. 26, 2020	Sep. 28, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Jun. 27, 2020	Jun. 29, 2019
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Transfers among level 1, 2, and 3	$ 0.0			$ 0.0			$ 0.0
Income recognized from change is asset	22.2	$ 2.6		25.9	$ 18.5
Royalty Pharma Contingent Milestone Payments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Net sales included in calculation for milestone payment							0.0	$ 337.5
Payments received			$ 250.0
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	22.2	2.6		25.9	18.5
Estimated fair valued contingent milestone payment	121.2	91.7		121.2	91.7		$ 95.3	$ 323.2	$ 99.0	$ 89.1
Payments received	0.0	$ 0.0		0.0	$ 250.0
Royalty Pharma 2020 Contingent Milestone Payments | Measured on a recurring basis | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Estimated fair valued contingent milestone payment	$ 121.2			$ 121.2
Royalty Pharma
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Volatility	30.00%	30.00%
Rate of return	6.84%	7.99%
Scenario, Forecast
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Royalty Pharma contingent payment sales threshold						$ 400.0
Scenario, Forecast | Royalty Pharma Contingent Milestone Payments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Royalty Pharma contingent payment sales threshold						400.0
Net sales threshold to trigger milestone payment						351.0
Income recognized from change is asset						$ 278.8
Discounted Cash Flow | Contingent Consideration | Measurement Input, Discount Rate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Contingent consideration payments: sales-based milestones (percent)				26.00%
RX | Discounted Cash Flow | Measurement Input, Discount Rate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Reporting unit, fair value (percent)	10.30%
RX | Discounted Cash Flow | Measurement Input, Long-term Growth Rate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Reporting unit, fair value (percent)	0.00%
Minimum | RX | Discounted Cash Flow
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Blended jurisdictional tax rates (percent)	19.10%
Maximum | RX | Discounted Cash Flow
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Blended jurisdictional tax rates (percent)	21.70%