Fair Value Measurement - (Details) - USD ($) $ in Thousands	Apr. 29, 2017	Apr. 30, 2016
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Available-for-sale securities:	$ 32,713	$ 24,672
Certificates of deposit
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Available-for-sale securities:	12,487	14,927
U.S. Government securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Available-for-sale securities:	400
U.S. Government sponsored entities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Available-for-sale securities:	12,238	8,522
Municipal obligations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Available-for-sale securities:	7,588	1,223
Recurring Basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Cash and cash equivalents	32,623	28,328
Restricted cash	216	198
Derivatives - asset position	64
Derivatives - liability position	(277)	(453)
Assets, net	63,448	50,790
Recurring Basis \| Certificates of deposit
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Available-for-sale securities:	12,487	14,927
Recurring Basis \| U.S. Government securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Available-for-sale securities:	400
Recurring Basis \| U.S. Government sponsored entities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Available-for-sale securities:	12,238	8,522
Recurring Basis \| Municipal obligations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Available-for-sale securities:	7,588	1,223
Recurring Basis \| Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Cash and cash equivalents	32,623	28,328
Restricted cash	216	198
Derivatives - asset position	0
Derivatives - liability position	0	0
Assets, net	33,239	28,526
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:	400
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 - asset position	64
Derivatives - liability position	(277)	(453)
Assets, net	32,100	24,219
Recurring Basis \| Level 2 \| Certificates of deposit
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Available-for-sale securities:	12,487	14,927
Recurring Basis \| Level 2 \| U.S. Government securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Available-for-sale securities:	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:	12,238	8,522
Recurring Basis \| Level 2 \| Municipal obligations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Available-for-sale securities:	7,588	1,223
Reported Value Measurement [Member] \| Recurring Basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Contingent liability	(1,891)	(1,955)
Estimate of Fair Value Measurement [Member] \| Recurring Basis \| Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Contingent liability	0	0
Estimate of Fair Value Measurement [Member] \| Recurring Basis \| Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Contingent liability	0	0
Estimate of Fair Value Measurement [Member] \| Recurring Basis \| Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Cash and cash equivalents	0	0
Restricted cash	0	0
Derivatives - asset position	0
Derivatives - liability position	0	0
Contingent liability	(1,891)	(1,955)
Assets, net	(1,891)	(1,955)
Estimate of Fair Value Measurement [Member] \| Recurring Basis \| Level 3 \| Certificates of deposit
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Available-for-sale securities:	0	0
Estimate of Fair Value Measurement [Member] \| Recurring Basis \| Level 3 \| U.S. Government securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Available-for-sale securities:	0
Estimate of Fair Value Measurement [Member] \| Recurring Basis \| Level 3 \| U.S. Government sponsored entities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Available-for-sale securities:	0	0
Estimate of Fair Value Measurement [Member] \| Recurring Basis \| Level 3 \| Municipal obligations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Available-for-sale securities:	$ 0	$ 0

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

+ References

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Amount of liability recognized arising from contingent consideration in a business combination.

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Fair value portion of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates.

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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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