Financial Instruments And Fair Value (Narrative) (Details) (USD $)
In Millions, unless otherwise specified

9 Months Ended

Jan. 27, 2012

Schedule of Fair Value of Separate Accounts by Major Category of Investment [Line Items]

Auction rate securities

All of our auction rate securities (ARSs) are classified as other non-current assets and are backed by pools of student loans guaranteed by the U.S. Department of Education. As of January 27, 2012, we recorded cumulative net temporary impairment charges of $3.4 million in accumulated other comprehensive income (AOCI). Prior to the three months ended October 28, 2011, we estimated the fair value for each individual ARS using an income (discounted cash flow) approach that incorporates both observable and unobservable inputs to discount the expected future cash flows. Key inputs into the discounted cash flow analysis include managements' expectation of when the principal amount will be recovered either through redemption at par, a refinancing event by the issuer, and/or marketability adjustments. Beginning October 28, 2011, we included the market approach to the valuation technique in order to incorporate secondary market activity into our estimated fair value for each individual ARS. This change had no material impact on the valuation of our ARS portfolio. Based on our ability to access our cash and other short-term investments, our expected operating cash flows, and our other sources of cash, we do not intend to sell these investments prior to recovery of value. We will continue to monitor our ARS investments in light of the current debt market environment and evaluate these investments for impairment and classification.

Auction Rate Securities [Member]

Schedule of Fair Value of Separate Accounts by Major Category of Investment [Line Items]

Cumulative net temporary charges within accumulated other comprehensive income

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