Goodwill By Reportable Segment (Details) - USD ($) $ in Thousands	Oct. 02, 2015	Dec. 31, 2014
Goodwill [Line Items]
Goodwill	$ 249,587	$ 241,975
Accumulated impairment of goodwill	(151,229)	(151,229)
Total	98,358	90,746
Laser Products
Goodwill [Line Items]
Goodwill	132,954	132,954
Accumulated impairment of goodwill	(102,461)	(102,461)
Total	30,493	30,493
Vision Technologies
Goodwill [Line Items]
Goodwill	82,730	82,730
Accumulated impairment of goodwill	(31,722)	(31,722)
Total	51,008	51,008
Precision Motion
Goodwill [Line Items]
Goodwill	33,903	26,291
Accumulated impairment of goodwill	(17,046)	(17,046)
Total	$ 16,857	$ 9,245