Segments - Operations by geographic area (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended										12 Months Ended
	Jan. 31, 2015		Oct. 31, 2014	Jul. 31, 2014	Apr. 30, 2014	Jan. 31, 2014		Oct. 31, 2013	Jul. 31, 2013	Apr. 30, 2013	Jan. 31, 2015		Jan. 31, 2014		Jan. 31, 2013
Segment Reporting Information [Line Items]
Net revenue	$ 664.6		$ 618.0	$ 637.1	$ 592.5	$ 586.6		$ 555.2	$ 561.7	$ 570.4	$ 2,512.2		$ 2,273.9		$ 2,312.2
Total long-lived assets	159.2	[1]				130.3	[1]				159.2	[1]	130.3	[1]
Americas
Segment Reporting Information [Line Items]
Net revenue											898.0		818.9		836.2
Total long-lived assets	111.9	[1]				91.9	[1]				111.9	[1]	91.9	[1]
Americas | U.S.
Segment Reporting Information [Line Items]
Net revenue											736.4		672.3		672.1
Total long-lived assets	108.8	[1]				89.0	[1]				108.8	[1]	89.0	[1]
Americas | Other Americas
Segment Reporting Information [Line Items]
Net revenue											161.6		146.6		164.1
Total long-lived assets	3.1	[1]				2.9	[1]				3.1	[1]	2.9	[1]
Europe Middle East And Africa [Member]
Segment Reporting Information [Line Items]
Net revenue											980.0		851.8		868.5
Europe, Middle East, and Africa | Europe Middle East And Africa [Member]
Segment Reporting Information [Line Items]
Total long-lived assets	25.0	[1]				27.2	[1]				25.0	[1]	27.2	[1]
Asia Pacific
Segment Reporting Information [Line Items]
Net revenue											634.2		603.2		607.5
Total long-lived assets	22.3	[1]				11.2	[1]				22.3	[1]	11.2	[1]
Asia Pacific | Japan
Segment Reporting Information [Line Items]
Net revenue											269.0		274.5		278.3
Asia Pacific | Other Asia Pacific
Segment Reporting Information [Line Items]
Net revenue											$ 365.2		$ 328.7		$ 329.2

[1] Long-lived assets exclude deferred tax assets, marketable securities, goodwill, and other intangible assets. Prior period amounts have been updated to conform to the current period's presentation.