Stock-based Compensation Expense Stock Based Compensation Expense (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Oct. 31, 2012	Oct. 31, 2011	Oct. 31, 2012	Oct. 31, 2011
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Share-based Compensation	$ 51.9	$ 25.6	$ 118.8	$ 78.8
Employee Service Share-based Compensation, Tax Benefit from Compensation Expense	(10.7)	(5.9)	(26.7)	(19.3)
Allocated Share-based Compensation Expense, Net of Tax	41.2	19.7	92.1	59.5
Cost of Sales [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Allocated Share-based Compensation Expense	1.3	0.9	3.8	2.8
Selling and Marketing Expense [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Allocated Share-based Compensation Expense	16.7	11.7	47.4	34.8
Other Research and Development Expense [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Allocated Share-based Compensation Expense	28.1	8.9	49.6	27.6
General and Administrative Expense [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Allocated Share-based Compensation Expense	5.8	4.1	18.0	13.6
Performance Shares [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Allocated Share-based Compensation Expense	$ 1.9		$ 5.2	$ 0