Commitments (Narrative) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Jan. 31, 2012	Jan. 31, 2011	Jan. 31, 2010
Commitments [Line Items]
Total operating lease commitment balance	$ 667.8
Rent expense	70.3	52.8	47.3
Letters Of Credit [Member]
Commitments [Line Items]
Value of outstanding letters of credit	17.5
Letters of credit maturity dates	April 2030
Computer Equipment And Other Leases [Member]
Commitments [Line Items]
Total operating lease commitment balance	60.1
Facilities Space [Member]
Commitments [Line Items]
Total operating lease commitment balance	607.7
50 Fremont St. [Member]
Commitments [Line Items]
Rentable office square feet	400,000
Lease term (in years)	18
Cost of lease	$ 209