Depreciation and Amortization Expenses by Reportable Segment (Details) - USD ($) $ in Thousands	3 Months Ended
	Apr. 03, 2020	Mar. 29, 2019
Depreciation and Amortization Expenses
Depreciation and amortization expenses	$ 9,330	$ 9,074
Unallocated Corporate and Shared Services
Depreciation and Amortization Expenses
Depreciation and amortization expenses	51	55
Photonics | Operating Segments
Depreciation and Amortization Expenses
Depreciation and amortization expenses	2,649	2,621
Vision | Operating Segments
Depreciation and Amortization Expenses
Depreciation and amortization expenses	5,277	5,029
Precision Motion | Operating Segments
Depreciation and Amortization Expenses
Depreciation and amortization expenses	$ 1,353	$ 1,369