Integration and Acquisition Costs (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Business Acquisition [Line Items]
Integration and acquisition costs (credits)	$ 179.3	$ 343.7	$ 419.0	$ 459.7
Baxalta
Business Acquisition [Line Items]
Integration and acquisition costs (credits)	419.0	343.7	179.3	459.7
Asset impairments | Baxalta
Business Acquisition [Line Items]
Integration and acquisition costs (credits)	5.9		143.4
Third-party professional fees | Baxalta
Business Acquisition [Line Items]
Integration and acquisition costs (credits)	21.2		43.1
Integration costs		50.4		85.6
Change in fair value of contingent consideration payable
Business Acquisition [Line Items]
Integration costs	27.0	151.2	45.9	147.7
Facility consolidations | Baxalta
Business Acquisition [Line Items]
Integration and acquisition costs (credits)	3.1		14.8
Integration costs		17.2		41.7
Employee severance and acceleration of stock compensation | Baxalta
Business Acquisition [Line Items]
Integration and acquisition costs (credits)	9.2		15.0
Integration costs		$ 80.2		$ 117.1
Takeda | Third-party professional fees
Business Acquisition [Line Items]
Integration and acquisition costs (credits)	64.0		64.0
Takeda | Severance and employee benefits
Business Acquisition [Line Items]
Integration and acquisition costs (credits)	$ 4.0		4.0
Oncology | Disposal Group | Third-party professional fees
Business Acquisition [Line Items]
Integration and acquisition costs (credits)			37.5
Oncology | Disposal Group | Severance and employee benefits
Business Acquisition [Line Items]
Integration and acquisition costs (credits)			$ 2.2