Acquisitions - Summary of Fair Value of Assets Acquired and Liabilities Assumed by Major Class (Detail) (USD $) In Millions, unless otherwise specified	0 Months Ended		12 Months Ended		0 Months Ended
	Jun. 27, 2014	May 29, 2014	Jan. 31, 2015	Jan. 31, 2014	Nov. 21, 2013	Jan. 31, 2013	Feb. 06, 2014
Business Acquisition [Line Items]
Goodwill			$ 1,456.2	$ 1,009.9		$ 871.5
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
Payments to acquire business	51.2
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		78.9	80.6
Deferred Revenue			0
Deferred tax (liability) asset			(1.7)
Net tangible assets			(0.3)
Total			88.0
Payments to acquire business		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
Other
Business Acquisition [Line Items]
Goodwill			180.6	67.0
Deferred Revenue			(0.4)
Deferred tax (liability) asset			(2.1)	0.7
Net tangible assets			1.3	1.5
Total				89.7
Payments to acquire business			234.5	89.7
Other | Developed technologies
Business Acquisition [Line Items]
Intangible assets			39.0	15.9
Other | Customer relationships
Business Acquisition [Line Items]
Intangible assets			9.8	2.8
Other | Trade name
Business Acquisition [Line Items]
Intangible assets			6.3	1.8
Graitec SA
Business Acquisition [Line Items]
Goodwill				73.4	64.1
Deferred tax (liability) asset				(6.2)
Net tangible assets				0
Total				87.0
Payments to acquire business					87.0
Graitec SA | Developed technologies
Business Acquisition [Line Items]
Intangible assets				15.9
Graitec SA | Customer relationships
Business Acquisition [Line Items]
Intangible assets				2.2
Graitec SA | Trade name
Business Acquisition [Line Items]
Intangible assets				$ 1.7