Goodwill By Reportable Segment (Details) - USD ($) $ in Thousands	Apr. 01, 2016	Dec. 31, 2015
Goodwill [Line Items]
Goodwill	$ 254,642	$ 254,685
Accumulated impairment of goodwill	(151,229)	(151,229)
Total	103,413	103,456
Laser Products
Goodwill [Line Items]
Goodwill	136,278	136,321
Accumulated impairment of goodwill	(102,461)	(102,461)
Total	33,817	33,860
Vision Technologies
Goodwill [Line Items]
Goodwill	84,401	84,401
Accumulated impairment of goodwill	(31,722)	(31,722)
Total	52,679	52,679
Precision Motion
Goodwill [Line Items]
Goodwill	33,963	33,963
Accumulated impairment of goodwill	(17,046)	(17,046)
Total	$ 16,917	$ 16,917

Amount after accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 20
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=35741047&loc=d3e13816-109267

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 20
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6388280&loc=d3e13770-109266

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Amount before accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

+ 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,h)
-URI http://asc.fasb.org/extlink&oid=35741047&loc=d3e13816-109267

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Amount of accumulated impairment loss for an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

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