Property and Equipment, Net of Accumulated Depreciation (Details) - USD ($) $ in Millions	12 Months Ended
	May 31, 2016	May 31, 2015	May 31, 2014
Property, Plant and Equipment [Line Items]
Total property and equipment, gross	$ 1,012.2	$ 973.4
Less: Accumulated depreciation	659.2	619.5
Property and equipment, net of accumulated depreciation	353.0	353.9
Depreciation expense	99.2	92.1	$ 89.1
Land and Improvements [Member]
Property, Plant and Equipment [Line Items]
Total property and equipment, gross	8.3	8.3
Buildings and Improvements [Member]
Property, Plant and Equipment [Line Items]
Total property and equipment, gross	103.0	102.1
Data Processing Equipment [Member]
Property, Plant and Equipment [Line Items]
Total property and equipment, gross	196.1	190.9
Software [Member]
Property, Plant and Equipment [Line Items]
Total property and equipment, gross	447.5	391.8
Furniture, Fixtures, and Equipment [Member]
Property, Plant and Equipment [Line Items]
Total property and equipment, gross	125.0	145.6
Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Total property and equipment, gross	108.2	106.2
Construction in Progress [Member]
Property, Plant and Equipment [Line Items]
Total property and equipment, gross	$ 24.1	$ 28.5