Depreciation and Amortization by Reportable Segments (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Apr. 01, 2016
Depreciation and Amortization
Depreciation and amortization	$ 6,482	$ 5,831
Photonics
Depreciation and Amortization
Depreciation and amortization	3,244	1,544
Vision
Depreciation and Amortization
Depreciation and amortization	2,437	3,100
Precision Motion
Depreciation and Amortization
Depreciation and amortization	566	614
Unallocated Corporate and Shared Services
Depreciation and Amortization
Depreciation and amortization	$ 235	$ 573