Computer Equipment, Software, Furniture and Leasehold Improvements, Net (Details) - USD ($) $ in Millions	Apr. 30, 2017	Jan. 31, 2017
Property, Plant and Equipment [Line Items]
Computer software, hardware, leasehold improvements, furniture and equipment, gross	$ 553.4	$ 544.1
Less: Accumulated depreciation	(403.0)	(385.5)
Computer software, hardware, leasehold improvements, furniture and equipment, net	150.4	158.6
Computer hardware, at cost
Property, Plant and Equipment [Line Items]
Computer software, hardware, leasehold improvements, furniture and equipment, gross	210.0	206.1
Computer software, at cost
Property, Plant and Equipment [Line Items]
Computer software, hardware, leasehold improvements, furniture and equipment, gross	75.9	73.5
Leasehold improvements, land and buildings, at cost
Property, Plant and Equipment [Line Items]
Computer software, hardware, leasehold improvements, furniture and equipment, gross	208.1	206.3
Furniture and equipment, at cost
Property, Plant and Equipment [Line Items]
Computer software, hardware, leasehold improvements, furniture and equipment, gross	$ 59.4	$ 58.2