Property, Plant and Equipment (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended			6 Months Ended				6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012	Dec. 31, 2012	Jun. 30, 2013 Hillerod, Denmark Facility [Member]	Sep. 30, 2012 Hillerod, Denmark Facility [Member]	Jun. 30, 2013 Cambridge Leases [Member]	Dec. 31, 2012 Cambridge Leases [Member]	Jun. 30, 2013 Eisai [Member]	Jun. 30, 2013 Minimum [Member] Cambridge Leases [Member]	Jun. 30, 2013 Maximum [Member] Cambridge Leases [Member]
Property, Plant and Equipment [Line Items]
Accumulated depreciation	$ (1,030.4)		$ (1,030.4)		$ (941.1)
Interest cost capitalization	1.9	8.6	5.0	16.8
Construction cost incurred not yet paid								131.9	86.5
Expected charges to vacate building											20.0	30.0
Transfer from construction in progress							$ 465.9
Average estimated useful life						20 years
Term Of Lease										10 years
Cancellation Period of Lease										5 years