Summary of Significant Accounting Policies (Details) (USD $) In Billions, unless otherwise specified	12 Months Ended
	Oct. 31, 2011 Year institution	Oct. 31, 2010	Oct. 31, 2009
Summary of Significant Accounting Policies
Advertising	$ 1.2	$ 1.0	$ 0.7
Number of institution designed to limit exposure as per entity's policy	1
Estimated useful life for purchased intangible assets, low end of range (in years)	1
Estimated useful life for purchased intangible assets, high end of range (in years)	10
Accounts Receivable | Major Customers
Concentration Risk
Number of largest distributor and reseller receivable balances	10
Concentration of credit risk, percentage with 10 largest distributor and reseller receivable balances (as a percent)	18.00%	18.00%
Maximum amount of accounts receivable from a single customer used as a disclosure threshold (as a percent)	10.00%