Goodwill By Reportable Segment (Details) - USD ($) $ in Thousands	Oct. 02, 2020	Dec. 31, 2019	Jul. 31, 2019
Goodwill [Line Items]
Goodwill	$ 430,752	$ 425,939
Accumulated impairment of goodwill	(151,229)	(151,229)
Total	279,523	274,710	$ 44,162
Photonics
Goodwill [Line Items]
Goodwill	215,697	213,413
Accumulated impairment of goodwill	(102,461)	(102,461)
Total	113,236	110,952
Vision
Goodwill [Line Items]
Goodwill	162,580	160,086
Accumulated impairment of goodwill	(31,722)	(31,722)
Total	130,858	128,364
Precision Motion
Goodwill [Line Items]
Goodwill	52,475	52,440
Accumulated impairment of goodwill	(17,046)	(17,046)
Total	$ 35,429	$ 35,394