Weighted average amortization period of finite-lived intangible assets acquired either individually or as part of a group of assets, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 350

-SubTopic 30

-Section 50

-Paragraph 1

-Subparagraph (a)(3)

-URI http://asc.fasb.org/extlink&oid=26713463&loc=d3e16265-109275

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- Definition

Percentage of voting equity interests acquired at the acquisition date in the business combination.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 805

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (c)

-URI http://asc.fasb.org/extlink&oid=25497992&loc=d3e1392-128463

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Amount of increase in assets, excluding financial assets, lacking physical substance with a definite life, resulting from a business combination.

+ References

No definition available.

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- Definition

The aggregate total of expenses of managing and administering the affairs of an entity, including affiliates of the reporting entity, which are not directly or indirectly associated with the manufacture, sale or creation of a product or product line.

+ References

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- Definition

Amount of increase in asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized resulting from a business combination.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 350

-SubTopic 20

-Section 50

-Paragraph 1

-Subparagraph (a)

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- Definition

Total revenue from sale of goods and services rendered during the reporting period, in the normal course of business, reduced by sales returns and allowances, and sales discounts.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 225

-SubTopic 10

-Section S99

-Paragraph 2

-Subparagraph (SX 210.5-03.1)

-URI http://asc.fasb.org/extlink&oid=26872669&loc=d3e20235-122688

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 1

-Article 5

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Business Combination (Details) (USD $)	3 Months Ended		9 Months Ended		3 Months Ended
Business Combination (Details) (USD $)	Jan. 31, 2015	Jan. 25, 2014	Jan. 31, 2015	Jan. 25, 2014	Nov. 01, 2014	Aug. 11, 2014
Business Acquisition [Line Items]
Percentage of voting interests acquired						100.00%
Goodwill acquired during period			$ 1,244,000us-gaap_GoodwillAcquiredDuringPeriod
Net sales	118,123,000us-gaap_SalesRevenueNet	115,369,000us-gaap_SalesRevenueNet	457,856,000us-gaap_SalesRevenueNet	415,730,000us-gaap_SalesRevenueNet
General and administrative	7,133,000us-gaap_GeneralAndAdministrativeExpense	6,685,000us-gaap_GeneralAndAdministrativeExpense	22,890,000us-gaap_GeneralAndAdministrativeExpense	20,788,000us-gaap_GeneralAndAdministrativeExpense
Data Display
Business Acquisition [Line Items]
Goodwill acquired during period					1,244,000
International
Business Acquisition [Line Items]
Goodwill acquired during period			1,244,000
Net sales	26,615,000	18,384,000	74,641,000	61,799,000
International \| Data Display
Business Acquisition [Line Items]
Net sales			4,900,000
General and administrative			400,000
Transportation
Business Acquisition [Line Items]
Goodwill acquired during period			0
Net sales	9,479,000	13,531,000	34,807,000	41,811,000
Unpatented Technology \| Data Display
Business Acquisition [Line Items]
Acquired finite-lived intangible asset					500,000
Weighted average useful life					20 years
Customer Relationships \| Data Display
Business Acquisition [Line Items]
Acquired finite-lived intangible asset					$ 100,000
Weighted average useful life					18 years