Cash Flow Information - Change in Operating Assets and Liabilities (Details) - USD ($) $ in Thousands	12 Months Ended
Apr. 28, 2018	Apr. 29, 2017	Apr. 30, 2016
(Increase) decrease:
Accounts receivable	$ 2,266	$ (2,718)	$ 3,789
Long-term receivables	1,548	2,213	2,851
Inventories	(8,517)	3,581	(5,100)
Costs and estimated earnings in excess of billings	5,911	(6,203)	4,867
Prepaid expenses and other current assets	(1,252)	(980)	1,290
Income taxes receivable	(4,747)	4,201	1,061
Investment in affiliates and other assets	(413)	611	776
Increase (decrease):
Current marketing obligations and other payables	(358)	857	21
Accounts Payable	(2,573)	5,544	(9,926)
Customer deposits	(53)	(1,514)	(941)
Accrued expenses	3,830	2,351	776
Warranty obligations	346	(2,986)	4,726
Billings in excess of costs and estimated earnings	1,034	536	(13,436)
Long-term warranty obligations	1,729	389	(710)
Income taxes payable	(592)	1,331	(37)
Deferred revenue	2,499	1,256	2,120
Long-term marketing obligations and other payables	379	(43)	(456)
Change in operating assets and liabilities	$ 1,863	$ 7,204	$ (9,881)

Increase (Decrease) In Long-Term Warranty Obligation

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- Definition

Increase (Decrease) In Short-Term Warranty Obligation

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No definition available.

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- Definition

Increase (decrease) in Current marketing obligations and other payables

+ References

No definition available.

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- Definition

The increase (decrease) during the reporting period in the aggregate amount of liabilities incurred (and for which invoices have typically been received) and payable to vendors for goods and services received that are used in an entity's business.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3602-108585

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- Definition

The increase (decrease) during the reporting period in amount due within one year (or one business cycle) from customers for the credit sale of goods and services.

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The increase (decrease) during the period in the amount due for taxes based on the reporting entity's earnings or attributable to the entity's income earning process (business presence) within a given jurisdiction.

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The increase (decrease) during the reporting period in the aggregate amount of expenses incurred but not yet paid.

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The increase (decrease) during the reporting period in the liability reflecting cash payments received before the related costs have been incurred.

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- Definition

Amount of increase (decrease) in the asset reflecting the cost incurred on uncompleted contracts in excess of related billings.

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- Definition

The increase (decrease) during the period in the amount of customer money held in customer accounts, including security deposits, collateral for a current or future transactions, initial payment of the cost of acquisition or for the right to enter into a contract or agreement.

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The increase (decrease) during the reporting period, excluding the portion taken into income, in the liability reflecting revenue yet to be earned for which cash or other forms of consideration was received or recorded as a receivable.

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The increase (decrease) during the reporting period in income taxes receivable, which represents the amount due from tax authorities for refunds of overpayments or recoveries of income taxes paid.

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The increase (decrease) during the reporting period in the aggregate value of all inventory held by the reporting entity, associated with underlying transactions that are classified as operating activities.

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The increase (decrease) during the reporting period in the amount due within one year (or one business cycle) of receivables that were originally due beyond one year (or one business cycle).

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Amount of increase (decrease) in operating assets classified as other.

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Amount of increase (decrease) in operating assets after deduction of operating liabilities classified as other.

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Amount of increase (decrease) in operating liabilities classified as other.

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- Definition

Amount of increase (decrease) in prepaid expenses, and assets classified as other.

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