Computer Equipment, Software, Furniture and Leasehold Improvements, Net (Details) (USD $) In Millions, unless otherwise specified	Apr. 30, 2014	Jan. 31, 2014
Property, Plant and Equipment [Abstract]
Computer software, at cost	$ 83.9	$ 80.9
Computer hardware, at cost	171.2	163.0
Leasehold improvements, land and buildings, at cost	172.1	163.7
Furniture and equipment, at cost	55.7	51.7
Computer software, hardware, leasehold improvements, furniture and equipment, gross	482.9	459.3
Less: Accumulated depreciation	(340.8)	(329.0)
Computer software, hardware, leasehold improvements, furniture and equipment, net	$ 142.1	$ 130.3