Summary of Significant Accounting Policies Restructuring Reserve (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Jan. 31, 2014
Restructuring Reserve [Roll Forward]
Opening balance	$ 10
Charges	51
Cash payments	(40)
Closing balance	21
Severance Costs
Restructuring Reserve [Roll Forward]
Opening balance	8
Charges	10
Cash payments	(17)
Closing balance	1
Lease Termination and Facility Consolidation Expenses
Restructuring Reserve [Roll Forward]
Opening balance	2
Charges	41
Cash payments	(23)
Closing balance	$ 20