Summary of Restructuring Costs for Each Segment and Unallocated Corporate and Shared Services Costs (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 28, 2019	Jun. 29, 2018	Jun. 28, 2019	Jun. 29, 2018
Restructuring Cost And Reserve [Line Items]
Restructuring costs	$ 2,134	$ 988	$ 3,370	$ 988
2019 Restructuring
Restructuring Cost And Reserve [Line Items]
Restructuring costs	1,965		2,932
Photonics | 2019 Restructuring
Restructuring Cost And Reserve [Line Items]
Restructuring costs	1,357		1,550
Vision | 2019 Restructuring
Restructuring Cost And Reserve [Line Items]
Restructuring costs	306		656
Precision Motion | 2019 Restructuring
Restructuring Cost And Reserve [Line Items]
Restructuring costs	147		194
Unallocated Corporate and Shared Services | 2019 Restructuring
Restructuring Cost And Reserve [Line Items]
Restructuring costs	$ 155		$ 532