Property, Plant and Equipment (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012	Dec. 31, 2012
Property, Plant and Equipment [Line Items]
Accumulated depreciation	$ (1,074.0)		$ (1,074.0)		$ (941.1)
Interest cost capitalization	2.2	6.6	5.7	23.4
Cambridge Leases [Member]
Property, Plant and Equipment [Line Items]
Derecognition of construction in progress assets	47.7		47.7
Construction cost incurred not yet paid	101.3		101.3		86.5
Expected charges to vacate building			25.0
Hillerod, Denmark Facility [Member]
Property, Plant and Equipment [Line Items]
Transfer from construction in progress		$ 465.9		$ 465.9
Average estimated useful life			20 years
Eisai [Member]
Property, Plant and Equipment [Line Items]
Term Of Lease			10 years
Cancellation Period of Lease			5 years