Property, Plant and Equipment Property, Plant and Equipment (Details 1) - Eisai $ in Millions	3 Months Ended
	Sep. 30, 2015 USD ($)
Property, Plant and Equipment
Research Triangle Park facility purchase	$ 104.8
Building
Property, Plant and Equipment
Research Triangle Park facility purchase	58.6
Machinery and Equipment
Property, Plant and Equipment
Research Triangle Park facility purchase	25.9
Land
Property, Plant and Equipment
Research Triangle Park facility purchase	$ 20.3