Summary of Restructuring Costs for Each Segment and Unallocated Corporate Costs (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jul. 01, 2016	Jul. 03, 2015	Jul. 01, 2016	Jul. 03, 2015
Restructuring Cost And Reserve [Line Items]
Restructuring charges	$ 1,972	$ 384	$ 4,684	$ 2,137
2016 Restructuring
Restructuring Cost And Reserve [Line Items]
Restructuring charges	2,076		4,576
2016 Restructuring | Laser Products
Restructuring Cost And Reserve [Line Items]
Restructuring charges	299		768
2016 Restructuring | Vision Technologies
Restructuring Cost And Reserve [Line Items]
Restructuring charges	1,719		3,458
2016 Restructuring | Precision Motion
Restructuring Cost And Reserve [Line Items]
Restructuring charges	19		106
2016 Restructuring | Unallocated Corporate and Shared Services
Restructuring Cost And Reserve [Line Items]
Restructuring charges	$ 39		$ 244