Fair Value Measurement (Details) (USD $) In Thousands, unless otherwise specified	Jan. 31, 2015	Apr. 26, 2014
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Available-for-sale securities:	$ 25,662us-gaap_AvailableForSaleSecurities	$ 25,398us-gaap_AvailableForSaleSecurities
Certificates of deposit
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Available-for-sale securities:	9,673	7,734
U.S. Government securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Available-for-sale securities:	1,001	2,002
U.S. Government sponsored entities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Available-for-sale securities:	8,650	8,341
Municipal obligations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Available-for-sale securities:	6,338	7,321
Recurring Basis \| Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Cash and cash equivalents	41,751	45,054
Restricted cash	772	514
Derivatives-currency forward contract, asset	0
Derivatives - currency forward contracts, liability		0
Assets, net	43,524	47,570
Recurring Basis \| Level 1 \| Certificates of deposit
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Available-for-sale securities:	0	0
Recurring Basis \| Level 1 \| U.S. Government securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Available-for-sale securities:	1,001	2,002
Recurring Basis \| Level 1 \| U.S. Government sponsored entities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Available-for-sale securities:	0	0
Recurring Basis \| Level 1 \| Municipal obligations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Available-for-sale securities:	0	0
Recurring Basis \| Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Cash and cash equivalents	0	0
Restricted cash	0	0
Derivatives-currency forward contract, asset	643
Derivatives - currency forward contracts, liability		85
Assets, net	25,304	23,311
Recurring Basis \| Level 2 \| Certificates of deposit
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Available-for-sale securities:	9,673	7,734
Recurring Basis \| Level 2 \| U.S. Government securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Available-for-sale securities:	0	0
Recurring Basis \| Level 2 \| U.S. Government sponsored entities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Available-for-sale securities:	8,650	8,341
Recurring Basis \| Level 2 \| Municipal obligations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Available-for-sale securities:	6,338	7,321
Recurring Basis \| Total
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Cash and cash equivalents	41,751	45,054
Restricted cash	772	514
Derivatives-currency forward contract, asset	643
Derivatives - currency forward contracts, liability		85
Assets, net	68,828	70,881
Recurring Basis \| Total \| Certificates of deposit
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Available-for-sale securities:	9,673	7,734
Recurring Basis \| Total \| U.S. Government securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Available-for-sale securities:	1,001	2,002
Recurring Basis \| Total \| U.S. Government sponsored entities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Available-for-sale securities:	8,650	8,341
Recurring Basis \| Total \| Municipal obligations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Available-for-sale securities:	$ 6,338	$ 7,321

Assets (Liabilities), Net, Fair Value Disclosure

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Restricted Cash and Cash Equivalents, Fair Value Disclosure

+ References

No definition available.

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Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

-SubTopic 10

-Section 25

-Paragraph 1

-Subparagraph (b)

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-Name Accounting Standards Codification

-Topic 320

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-Section 50

-Paragraph 5

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-Name Accounting Standards Codification

-Topic 320

-SubTopic 10

-Section 45

-Paragraph 1

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+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Cash

-URI http://asc.fasb.org/extlink&oid=6506951

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-Publisher FASB

-Name Accounting Standards Codification

-Glossary Cash Equivalents

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- Definition

Fair value portion of asset contracts related to the exchange of different currencies, including, but not limited to, foreign currency options, forward contracts, and swaps.

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Fair value portion of liability contracts related to the exchange of different currencies, including, but not limited to, foreign currency options, forward (delivery or nondelivery) contracts, and swaps entered into.

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