Goodwill and Intangible Assets - Intangible Assets Narrative (Details) - USD ($)								3 Months Ended								6 Months Ended		12 Months Ended
		Mar. 01, 2021	Sep. 26, 2020	Jun. 27, 2020	Dec. 31, 2019		Sep. 29, 2018	Dec. 31, 2020		Sep. 30, 2020	Dec. 31, 2019		Sep. 28, 2019	Jun. 29, 2019	Sep. 29, 2018	Dec. 31, 2020		Dec. 31, 2020		Dec. 31, 2019		Dec. 31, 2018		Sep. 30, 2018
Schedule of Definite and Indefinite Intangible Asset [Line Items]
Cash consideration in definitive agreement to sell																		$ 187,800,000		$ 182,500,000		$ 5,200,000
Goodwill impairment charge																		346,800,000		109,200,000
Goodwill					$ 4,116,700,000			$ 3,768,800,000			$ 4,116,700,000					$ 3,768,800,000		3,768,800,000		4,116,700,000		3,979,800,000
Impairment charges								144,400,000		$ 202,400,000	141,600,000		$ 10,900,000	$ 27,800,000				346,800,000		184,500,000		224,400,000
Amortization of intangible assets																		294,700,000		305,500,000		333,600,000
Impairment of intangible assets, indefinite-lived													$ 18,100,000
RX | Subsequent Event
Schedule of Definite and Indefinite Intangible Asset [Line Items]
Total consideration in definitive agreement to sell		$ 1,550,000,000
Cash consideration in definitive agreement to sell		1,500,000,000
R&D milestone payments assumed by purchaser in definitive agreement to sell		$ 50,000,000.0
RX
Schedule of Definite and Indefinite Intangible Asset [Line Items]
Goodwill impairment charge			$ 202,400,000		109,200,000			144,400,000										346,800,000	[1]	109,200,000	[1]
Goodwill			$ 811,100,000		1,013,900,000	[1]		673,100,000	[1]		1,013,900,000	[1]				673,100,000	[1]	673,100,000	[1]	1,013,900,000	[1]	1,114,800,000	[1]
Reporting unit, percentage of fair value in excess of carrying amount (RX US more than percent in Sept. 2018, less than % at Dec. 31, 2019; CSC UK and Australia less than %; BCS and Oral Care International less than %; CSCA and Rx UK greater than %)														10.00%										25.00%
Impairment charges														$ 0
CSCI
Schedule of Definite and Indefinite Intangible Asset [Line Items]
Goodwill impairment charge	[2]																	0		0
Goodwill	[2]				1,203,700,000			1,190,700,000			1,203,700,000					1,190,700,000		1,190,700,000		1,203,700,000		1,151,300,000
CSCA
Schedule of Definite and Indefinite Intangible Asset [Line Items]
Goodwill impairment charge																		0		0
Goodwill					$ 1,899,100,000			1,905,000,000.0			$ 1,899,100,000					1,905,000,000.0		1,905,000,000.0		1,899,100,000		1,713,700,000
Generic Product Acquisition | RX
Schedule of Definite and Indefinite Intangible Asset [Line Items]
Impairment of intangible assets, definite-lived intangible																				27,800,000
In-process research and development
Schedule of Definite and Indefinite Intangible Asset [Line Items]
Impairment of intangible assets, indefinite-lived																				5,800,000		$ 8,700,000
Generic Benzaclin Product | RX
Schedule of Definite and Indefinite Intangible Asset [Line Items]
Impairment of intangible assets, definite-lived intangible																				21,200,000
Licensed Pain Relief Products | CSCI
Schedule of Definite and Indefinite Intangible Asset [Line Items]
Impairment of intangible assets, definite-lived intangible																				9,700,000
Evamist Branded Product | RX
Schedule of Definite and Indefinite Intangible Asset [Line Items]
Impairment of intangible assets, definite-lived intangible																				$ 10,800,000
Animal health | CSCA
Schedule of Definite and Indefinite Intangible Asset [Line Items]
Goodwill impairment charge															$ 136,700,000
Reclassified intangible assets							$ 5,400,000
Animal health | Brand | CSCA
Schedule of Definite and Indefinite Intangible Asset [Line Items]
Impairment of intangible assets, definite-lived intangible															27,700,000
Animal health | Developed Product Technology and Distribution Agreements | CSCA
Schedule of Definite and Indefinite Intangible Asset [Line Items]
Impairment of intangible assets, definite-lived intangible															41,600,000
Animal health | Supply Agreement | CSCA
Schedule of Definite and Indefinite Intangible Asset [Line Items]
Impairment of intangible assets, definite-lived intangible															2,800,000
Animal health | Trade name and trademark | CSCA
Schedule of Definite and Indefinite Intangible Asset [Line Items]
Impairment of intangible assets, definite-lived intangible															$ 4,500,000
BCS | CSCI
Schedule of Definite and Indefinite Intangible Asset [Line Items]
Goodwill impairment charge				$ 0												0
Goodwill								$ 1,049,200,000								$ 1,049,200,000		$ 1,049,200,000
Reporting unit, percentage of fair value in excess of carrying amount (RX US more than percent in Sept. 2018, less than % at Dec. 31, 2019; CSC UK and Australia less than %; BCS and Oral Care International less than %; CSCA and Rx UK greater than %)				10.00%

[1] We had accumulated goodwill impairments of $109.2 million and $456.0 million as of December 31, 2019 and December 31, 2020, respectivel

[2] (1) We had accumulated goodwill impairments of $868.4 million as of December 31, 2019 and December 31, 2020.