Acquisitions Summary of Fair Value of Assets Acquired and Liabilities Assumed by Major Class (Details) (USD $) In Millions, unless otherwise specified	Jul. 31, 2013	Jan. 31, 2013
Business Acquisition [Line Items]
Goodwill acquired	$ 903.2	$ 871.5
Other Acquistions [Member]
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Deferred Tax Liabilities Noncurrent	0.7
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Noncurrent Assets	0.2
Goodwill acquired	33.6
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net	47.5
Other Acquistions [Member] | Developed Technology Rights [Member]
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles	9.3
Other Acquistions [Member] | Customer Relationships [Member]
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles	2.6
Other Acquistions [Member] | Trade Names [Member]
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles	$ 1.1