Note 2 - Business Acquisitions, Goodwill and Other Purchased Intangible Assets - Purchased Intangible Assets, Subject to Amortization (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 25, 2017	Dec. 31, 2016
Gross Carrying Amount	$ 32,393	$ 31,544
Accumulated Amortization	15,001	13,709
Ismeca Technology [Member]
Gross Carrying Amount	26,895	26,191
Accumulated Amortization	$ 14,428	13,241
Remaining Useful Life (Year)	3 years 292 days
Trade Names [Member]
Gross Carrying Amount	$ 5,498	5,353
Accumulated Amortization	$ 573	$ 468
Remaining Useful Life (Year)	13 years 182 days

Useful life of finite-lived intangible assets, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

No definition available.

+ Details

Name:	us-gaap_FiniteLivedIntangibleAssetUsefulLife
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Accumulated amount of amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 30
-Section 50
-Paragraph 2
-Subparagraph (a)(1)
-URI http://asc.fasb.org/extlink&oid=66006027&loc=d3e16323-109275

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount before amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

+ References

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Details

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Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis=us-gaap_TradeNamesMember
Namespace Prefix:
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Balance Type:
Period Type: