Investments - Sales and Maturities (Details) - USD ($) $ in Thousands	3 Months Ended
Jul. 28, 2018	Jul. 29, 2017
Sales of available-for-sale securities
Proceeds from sales	$ 4,762	$ 5,857
Gross realized gains	75	402
Gross realized losses	(55)	$ (221)
Fair value of available-for-sale securities by contractual maturity
Fair value, available-for-sale securities with contractual maturity within one year	12,500
Fair value, available-for-sale securities with contractual maturity within two to five years	18,900
Fair value, available-for-sale securities with contractual maturity within six to ten years	1,200
Fair value, available-for-sale securities with contractual maturity after ten years	$ 1,000

Amount of realized gain on investment in marketable securities.

No definition available.

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- Definition

Amount of realized loss on investment in marketable securities.

+ References

No definition available.

+ Details

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- References

No definition available.

+ Details

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- Definition

Fair value of available-for-sale debt securities maturing in the next rolling twelve months following the latest balance sheet. For interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

+ References

No definition available.

+ Details

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- Definition

Fair value of available-for-sale debt securities maturing after the tenth rolling twelve months following the latest balance sheet. For interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

+ References

No definition available.

+ Details

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- Definition

Fair value of available-for-sale debt securities maturing in the sixth through tenth rolling twelve months following the latest balance sheet. For interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

+ References

No definition available.

+ Details

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- Definition

Fair value of available-for-sale debt securities maturing in the second through fifth rolling twelve months following the latest balance sheet. For interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

+ References

No definition available.

+ Details

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- References

No definition available.

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- Definition

The cash inflow associated with the sale, maturity and collection of all investments such as debt, security and so forth during the period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 12
-URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3179-108585

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