Fair Value Measurements - Additional Information (Details)		3 Months Ended		9 Months Ended		12 Months Ended
	Mar. 27, 2017 USD ($)	Sep. 29, 2018 USD ($)	Sep. 30, 2017 USD ($)	Sep. 29, 2018 USD ($)	Sep. 30, 2017 USD ($)	Dec. 31, 2020 USD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Jun. 30, 2018 USD ($)	Jul. 01, 2017 USD ($)	Apr. 01, 2017 USD ($)	Dec. 31, 2016 USD ($)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Transfers among level 1, 2, and 3		$ 0		$ 0				$ 0
Cash proceeds from divestiture of businesses				5,000,000	$ 46,700,000
Change in financial assets		74,900,000	$ (2,600,000)	65,900,000	(24,200,000)
Net gain on reduction of contingent consideration					17,000,000
Measured on a recurring basis | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Potential contingent milestone payments		200,400,000		200,400,000				134,500,000
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]
Potential contingent milestone payments											$ 184,500,000
Increase (decrease) in fair value of milestone payment		74,900,000	(2,900,000)	65,900,000	(42,100,000)
Estimated fair valued contingent milestone payment		200,400,000	143,200,000	200,400,000	$ 143,200,000			$ 134,500,000	$ 125,500,000	$ 145,800,000		$ 0
Royalty Pharma 2018 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		67,700,000		53,200,000
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]
Increase (decrease) in fair value of milestone payment		$ 7,200,000		$ 12,700,000
Scenario, Forecast
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Potential contingent milestone payments						$ 67,400,000	$ 133,000,000
Fair value adjustment						400,000,000	250,000,000
Change in financial assets						332,600,000	117,000,000
Net sales threshold for milestone payment						$ 1,950,000,000	$ 1,850,000,000
Specialty Sciences
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Gain related to Royalty Pharma			$ 17,100,000
Royalty Pharma
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Sale price of divestiture - cash plus non-cash	$ 2,850,000,000
Cash proceeds from divestiture of businesses	2,200,000,000
2018 milestone payment	250,000,000
2020 milestone payment	$ 400,000,000
Rate of return				8.07%	8.06%
Measurement Input, Price Volatility | Royalty Pharma
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Volatility rate assumed			0.3		0.3
Measurement Input, Long-term Revenue Growth Rate [Member] | CHCA
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 | CHCA
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Reporting Unit, Discounted Cash Flow, Measurement Input		0.0975
Indefinite-lived Intangible Assets (Excluding Goodwill), Measurement Input		0.0975
Measurement Input, Tax Rate [Member] | CHCA
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