Other Consolidated Financial Statement Detail (Details Textual) € in Millions, $ in Millions	1 Months Ended	3 Months Ended								12 Months Ended
	Feb. 28, 2015 USD ($)	Dec. 31, 2015 USD ($)	Sep. 30, 2015 USD ($)	Jun. 30, 2015 USD ($)	Mar. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)	Sep. 30, 2014 USD ($)	Jun. 30, 2014 USD ($)	Mar. 31, 2014 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)	Dec. 31, 2015 EUR (€)	Dec. 31, 2014 EUR (€)	Jun. 30, 2013 EUR (€)	Dec. 31, 2011 EUR (€)
Business Acquisition [Line Items]
Increase to goodwill										$ 908.1	$ 527.3
Accrued expenses and other		$ 2,096.8				$ 1,817.7				2,096.8	1,817.7
Contingent consideration obligation										274.5	0.0
Prepaid taxes		550.6				57.6				550.6	57.6
Product, net		2,425.9	$ 2,391.7	$ 2,198.6	$ 2,172.3	2,287.0	$ 2,117.3	$ 2,056.3	$ 1,742.8	9,188.5	8,203.4	$ 5,542.3
Accrued expenses and other long-term deferred revenue		905.8				$ 650.1				905.8	650.1
Cambridge Leases
Business Acquisition [Line Items]
Derecognition of construction in progress assets												161.5
Solothurn
Business Acquisition [Line Items]
Accrued expenses and other		59.1								59.1
Convergence Pharmaceuticals
Business Acquisition [Line Items]
Contingent consideration obligation	$ 274.5
TECFIDERA
Business Acquisition [Line Items]
Product, net										3,638.4	2,909.2	$ 876.1
TECFIDERA | Fumapharm AG
Business Acquisition [Line Items]
Increase to goodwill										900.0	$ 600.0
TECFIDERA | Seven billion | Fumapharm AG
Business Acquisition [Line Items]
Increase to goodwill		300.0
Cumulative sales level		$ 7,000.0								$ 7,000.0
ITALY
Business Acquisition [Line Items]
Proposed settlement | €														€ 35.6	€ 33.3	€ 30.7
Loss contingency accrual | €															€ 15.4
Loss contingency, adjustment related to claim amount, percent															50.00%
Product, net								$ 53.5
Accrued expenses and other long-term deferred revenue | €													€ 75.0