Depreciation and Amortization Expenses by Reportable Segment (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jul. 02, 2021	Jul. 03, 2020	Jul. 02, 2021	Jul. 03, 2020
Depreciation and Amortization Expenses
Depreciation and amortization expenses	$ 9,875	$ 9,437	$ 19,724	$ 18,767
Unallocated Corporate and Shared Services
Depreciation and Amortization Expenses
Depreciation and amortization expenses	73	42	142	93
Photonics | Operating Segments
Depreciation and Amortization Expenses
Depreciation and amortization expenses	2,905	2,790	5,803	5,439
Vision | Operating Segments
Depreciation and Amortization Expenses
Depreciation and amortization expenses	5,279	5,272	10,554	10,549
Precision Motion | Operating Segments
Depreciation and Amortization Expenses
Depreciation and amortization expenses	$ 1,618	$ 1,333	$ 3,225	$ 2,686