Property, Plant and Equipment (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	May 31, 2016	May 31, 2017	May 31, 2016	May 31, 2015
Property, Plant and Equipment [Line Items]
Total at cost	$ 877.0	$ 920.8	$ 877.0
Less: Accumulated depreciation and amortization	(439.4)	(445.5)	(439.4)
Property, plant and equipment, net	437.6	475.3	437.6
Depreciation and amortization expense of property plant and equipment		36.2	36.7	$ 46.0
Asset impairments		6.8	14.4	$ 15.8
Land [Member]
Property, Plant and Equipment [Line Items]
Total at cost	77.4	77.5	77.4
Building [Member]
Property, Plant and Equipment [Line Items]
Total at cost	240.4	239.7	240.4
Capitalized software [Member]
Property, Plant and Equipment [Line Items]
Total at cost	196.0	202.0	196.0
Furniture, fixtures and equipment [Member]
Property, Plant and Equipment [Line Items]
Total at cost	221.5	224.7	221.5
Building and Leasehold improvements [Member]
Property, Plant and Equipment [Line Items]
Total at cost	141.7	176.9	$ 141.7
Property, Plant and Equipment, Additions		34.2
Website Development [Member]
Property, Plant and Equipment [Line Items]
Asset impairments		$ 5.7
Legacy Building Improvements [Member]
Property, Plant and Equipment [Line Items]
Asset impairments	$ 7.5