Acquisitions - Summary of Fair Value of Assets Acquired and Liabilities Assumed by Major Class (Detail) - USD ($) $ in Millions	Jan. 31, 2016	Jan. 31, 2015	May. 29, 2014	Feb. 06, 2014	Jan. 31, 2014
Business Acquisition [Line Items]
Goodwill	$ 1,535.0	$ 1,456.2			$ 1,009.9
netfabb
Business Acquisition [Line Items]
Goodwill	32.8
Deferred Revenue	(1.0)
Deferred tax (liability) asset	(3.9)
Net tangible assets	0.4
Total	42.5
netfabb | Developed technologies
Business Acquisition [Line Items]
Intangible assets	6.6
netfabb | Customer relationships
Business Acquisition [Line Items]
Intangible assets	6.2
netfabb | Trade name
Business Acquisition [Line Items]
Intangible assets	1.4
Other
Business Acquisition [Line Items]
Goodwill	64.5	180.6
Deferred Revenue	(0.7)	(0.4)
Deferred tax (liability) asset	(2.4)	(2.1)
Net tangible assets	0.5	1.3
Total	106.8	234.5
Other | Developed technologies
Business Acquisition [Line Items]
Intangible assets	27.3	39.0
Other | Customer relationships
Business Acquisition [Line Items]
Intangible assets	12.9	9.8
Other | Trade name
Business Acquisition [Line Items]
Intangible assets	$ 4.7	6.3
Shotgun Software Inc.
Business Acquisition [Line Items]
Goodwill		43.2
Deferred Revenue		(0.7)
Deferred tax (liability) asset		(2.6)
Net tangible assets		0.1
Total		54.5
Shotgun Software Inc. | Developed technologies
Business Acquisition [Line Items]
Intangible assets		5.4
Shotgun Software Inc. | Customer relationships
Business Acquisition [Line Items]
Intangible assets		7.5
Shotgun Software Inc. | Trade name
Business Acquisition [Line Items]
Intangible assets		1.6
Within Technologies Limited
Business Acquisition [Line Items]
Goodwill		80.6	$ 78.9
Deferred Revenue		0.0
Deferred tax (liability) asset		(1.7)
Net tangible assets		(0.3)
Total		88.0
Within Technologies Limited | Developed technologies
Business Acquisition [Line Items]
Intangible assets		4.6
Within Technologies Limited | Customer relationships
Business Acquisition [Line Items]
Intangible assets		3.6
Within Technologies Limited | Trade name
Business Acquisition [Line Items]
Intangible assets		1.2
Delcam plc
Business Acquisition [Line Items]
Goodwill		190.4		$ 166.0
Deferred Revenue		(10.4)
Deferred tax (liability) asset		(13.2)
Net tangible assets		32.7
Total		284.6
Delcam plc | Developed technologies
Business Acquisition [Line Items]
Intangible assets		28.9
Delcam plc | Customer relationships
Business Acquisition [Line Items]
Intangible assets		39.7
Delcam plc | Trade name
Business Acquisition [Line Items]
Intangible assets		$ 16.5