Income Taxes - Effective Income Tax (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Apr. 27, 2013	Apr. 28, 2012	Apr. 30, 2011
Income Tax Disclosure [Abstract]
Computed income tax expense at federal statutory rate	$ 10,825	$ 4,052	$ 7,732
State taxes, net of federal benefit	684	497	1,107
Research and development tax credit	(1,804)	(1,004)	(981)
Meals and entertainment	308	375	299
Stock compensation	466	842	959
Dividends paid to retirement plan	(616)	(522)	0
Domestic production activities deduction	(976)	(270)	(607)
Change in foreign deferred rates	0	(249)	0
Reversal of valuation allowance	0	(364)	0
Other, net	(737)	(269)	(612)
Effective income tax expense	$ 8,150	$ 3,088	$ 7,897

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The sum of the current income tax expense or benefit and the deferred income tax expense or benefit pertaining to pretax Income or Loss from continuing operations; income tax expense or benefit may include interest and penalties on tax uncertainties based on the entity's accounting policy.

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The portion of the difference between total income tax expense or benefit as reported in the Income Statement for the period and the expected income tax expense or benefit computed by applying the domestic federal statutory income tax rates to pretax income from continuing operations attributable to the deduction for dividends paid to employee stock ownership plans received under enacted tax laws.

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The portion of the difference between total income tax expense or benefit as reported in the Income Statement and the expected income tax expense or benefit computed by applying the domestic federal statutory income tax rates to pretax income from continuing operations attributable to changes in the valuation allowance for deferred tax assets in the period.

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The portion of the difference between total income tax expense or benefit as reported in the Income Statement for the period and the expected income tax expense or benefit computed by applying the domestic federal statutory income tax rates to pretax income from continuing operations attributable to the deduction for qualified production activities received under enacted tax laws.

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The portion of the difference, between total income tax expense or benefit as reported in the Income Statement for the period and the expected income tax expense or benefit computed by applying the domestic federal statutory income tax rates to pretax income from continuing operations, that is attributable to total foreign income tax expense or benefit. The foreign income tax expense or benefit difference represents the income tax expense or benefit at applicable domestic statutory income tax rates applied to foreign earnings or loss for the period versus the foreign income tax expense or benefit calculated by applying the appropriate foreign tax rates.

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The amount of income tax expense or benefit for the period computed by applying the domestic federal statutory tax rates to pretax income from continuing operations.

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The portion of the difference between total income tax expense or benefit as reported in the Income Statement for the period and the expected income tax expense or benefit computed by applying the domestic federal statutory income tax rates to pretax income from continuing operations attributable to nondeductible meal and entertainment expenses under enacted tax laws.

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The portion of the difference, between total income tax expense or benefit as reported in the Income Statement for the year/accounting period and the expected income tax expense or benefit computed by applying the domestic federal statutory income tax rates to pretax income from continuing operations, that is attributable to all other items not otherwise listed in the existing taxonomy.

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