Summary of Restructuring Charges by Reportable Segment (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Oct. 02, 2020	Sep. 27, 2019	Oct. 02, 2020	Sep. 27, 2019
Restructuring Cost And Reserve [Line Items]
Restructuring costs	$ 1,074	$ 1,466	$ 2,427	$ 4,836
2019 Restructuring
Restructuring Cost And Reserve [Line Items]
Restructuring costs	68	1,115	667	4,047
2019 Restructuring | Photonics
Restructuring Cost And Reserve [Line Items]
Restructuring costs	25	475	236	2,025
2019 Restructuring | Vision
Restructuring Cost And Reserve [Line Items]
Restructuring costs	13	367	304	1,023
2019 Restructuring | Precision Motion
Restructuring Cost And Reserve [Line Items]
Restructuring costs	$ 30	340	108	534
2019 Restructuring | Unallocated Corporate and Shared Services
Restructuring Cost And Reserve [Line Items]
Restructuring costs		$ (67)	$ 19	$ 465