Acquisitions and Other Transactions (Other Transactions) (Narrative) (Details) - USD ($) $ in Millions										3 Months Ended			9 Months Ended	12 Months Ended
	Dec. 01, 2018	Feb. 28, 2018	Dec. 25, 2017	Sep. 29, 2017	Jun. 19, 2017	Jun. 02, 2017	Mar. 29, 2017	Jan. 09, 2017	Aug. 05, 2016	Dec. 31, 2018	Sep. 30, 2018	Dec. 31, 2017	Sep. 30, 2018	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Aug. 31, 2018	Feb. 14, 2017
Business Acquisition [Line Items]
Ordinary shares issued for acquisition														$ 0.0	$ 0.0	$ 1,281.7
Acquisition purchase price											$ 463.0
Acquired intangible assets, weighted average useful life, in years			5 years												4 years
Meda AB
Business Acquisition [Line Items]
Acquisition purchase price									$ 5,300.0
Identified intangible assets												$ 8,060.7			$ 8,060.7
Meda AB | Product rights and licenses
Business Acquisition [Line Items]
Acquisition purchase price												$ 300.0
Identified intangible assets									$ 8,060.0
Acquired intangible assets, weighted average useful life, in years									20 years
Series of Individually Immaterial Business Acquisitions [Member]
Business Acquisition [Line Items]
Acquisition purchase price	$ 135.0				$ 256.7
Identified intangible assets					$ 252.5
ColdEeze
Business Acquisition [Line Items]
Acquisition purchase price								$ 50.0
Other companies
Business Acquisition [Line Items]
Acquired intangible assets, weighted average useful life, in years													5 years
Other companies | Product rights and licenses
Business Acquisition [Line Items]
Acquisition purchase price			$ 90.0	$ 40.0		$ 128.0							$ 220.0	$ 57.9	52.0
Cash paid to acquire asset															22.5
Expected future payments in 2017															$ 29.5
Acquired intangible assets, weighted average useful life, in years				5 years		5 years	15 years							5 years	15 months
Payments To Acquire Collaborative Agreement										$ 20.0			160.0
TOBI [Member]
Business Acquisition [Line Items]
Cash paid to acquire asset											240.0
Payments made in current year											130.0
Expected future payments in 2017											$ 93.0
Acquired intangible assets, weighted average useful life, in years											10 years
Payment for Contingent Consideration Liability, Financing Activities											$ 20.0
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net																	$ 91.0
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Financial Assets																	$ 574.8
Research and Development Expense | Other companies
Business Acquisition [Line Items]
Joint development and marketing agreement																		$ 50.0
Revance [Member]
Business Acquisition [Line Items]
Payments To Acquire Collaborative Agreement		$ 25.0
Revance [Member] | Maximum
Business Acquisition [Line Items]
Development Milestone Payments										100.0				$ 100.0
Sales Milestone Payments										$ 225.0				$ 225.0
Other companies
Business Acquisition [Line Items]
Payments To Acquire Collaborative Agreement													$ 53.7