Property, Plant and Equipment (Details Textual) (USD $) In Millions, unless otherwise specified	12 Months Ended								12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2013 Cambridge Leases	Dec. 31, 2012 Cambridge Leases	Dec. 31, 2011 Cambridge Leases	Dec. 31, 2013 Hillerod Denmark Facility	Sep. 30, 2013 Hillerod Denmark Facility	Dec. 31, 2013 Eisai
Property, Plant and Equipment
Depreciation expense	$ 187.8	$ 164.3	$ 143.9	$ 6.2	$ 11.4	$ 4.7
Interest cost capitalization related to construction in progress	7.8	25.4	32.6
Derecognition of construction in progress assets				161.5
Construction cost incurred not yet paid					86.5
Charges recognized to vacate building				27.2
Total cost	$ 2,869.0	$ 2,683.3						$ 465.9
Average estimated useful life							20 years
Term of lease				15 years					10 years
Cancellation Period of Lease									5 years