Stock-based Compensation Expense Stock Based Compensation Expense (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jul. 31, 2012	Jul. 31, 2011	Jul. 31, 2012	Jul. 31, 2011
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Share-based Compensation	$ 33.5	$ 27.3	$ 66.9	$ 53.2
Employee Service Share-based Compensation, Tax Benefit from Compensation Expense	(7.3)	(5.8)	(16.0)	(13.4)
Allocated Share-based Compensation Expense, Net of Tax	26.2	21.5	50.9	39.8
Cost of Sales [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Allocated Share-based Compensation Expense	1.2	1.0	2.5	1.9
Selling and Marketing Expense [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Allocated Share-based Compensation Expense	16.1	11.3	30.7	23.1
Other Research and Development Expense [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Allocated Share-based Compensation Expense	10.4	9.8	21.5	18.7
General and Administrative Expense [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Allocated Share-based Compensation Expense	5.8	5.2	12.2	9.5
Performance Shares [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Allocated Share-based Compensation Expense	$ 2.1		$ 3.3	$ 0