Stock-based Compensation Expense Stock Based Compensation Expense (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Apr. 30, 2012	Apr. 30, 2011
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Share-based Compensation	$ 33.4	$ 25.9
Employee Service Share-based Compensation, Tax Benefit from Compensation Expense	(8.7)	(7.6)
Allocated Share-based Compensation Expense, Net of Tax	24.7	18.3
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
Selling and Marketing Expense [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Allocated Share-based Compensation Expense	14.6	11.8
Other Research and Development Expense [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Allocated Share-based Compensation Expense	11.1	8.9
General and Administrative Expense [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Allocated Share-based Compensation Expense	$ 6.4	$ 4.3