Integration and acquisition costs (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014
Business Acquisition [Line Items]
Integration and acquisition costs	$ 89.9	$ 37.1	$ (46.8)	$ 155.8
Contingent consideration payable, current (within other current liabilities)	111.7		111.7		$ 194.5
NPS Pharma
Business Acquisition [Line Items]
Integration and acquisition costs	13.6		131.2
Lumena
Business Acquisition [Line Items]
Contingent consideration payable, current (within other current liabilities)	90.0		90.0
Acquisition and Integration Costs, Gross Amount
Business Acquisition [Line Items]
Change in fair value of contingent consideration		4.9
Acquisition and Integration Costs, Gross Amount | Viropharma
Business Acquisition [Line Items]
Integration and acquisition costs		32.2		129.5
Acquisition and Integration Costs, Gross Amount | NPS Pharma, Viropharma and the proposed combination with Baxalta
Business Acquisition [Line Items]
Integration and acquisition costs	30.7		149.7
Acquisition and Integration Costs, Gross Amount | Lumena and Lotus Tissue Repair
Business Acquisition [Line Items]
Change in fair value of contingent consideration			(196.5)
Acquisition and Integration Costs, Gross Amount | SARcode and Ferrokin Bioscience, Inc
Business Acquisition [Line Items]
Change in fair value of contingent consideration				26.3
Acquisition and Integration Costs, Gross Amount | Lumena
Business Acquisition [Line Items]
Change in fair value of contingent consideration	59.2
Acquisition and Integration Costs, Net Amount
Business Acquisition [Line Items]
Integration and acquisition costs	$ 89.9	$ 37.1	$ (46.8)	$ 155.8