Depreciation and Amortization by Reportable Segments (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jul. 03, 2015	Jun. 27, 2014	Jul. 03, 2015	Jun. 27, 2014
Depreciation and Amortization
Depreciation and amortization	$ 4,623	$ 6,322	$ 9,385	$ 11,151
Laser Products
Depreciation and Amortization
Depreciation and amortization	1,397	1,554	2,979	3,220
Vision Technologies
Depreciation and Amortization
Depreciation and amortization	2,082	3,716	4,340	5,807
Precision Motion
Depreciation and Amortization
Depreciation and amortization	689	505	1,162	1,007
Unallocated Corporate and Shared Services
Depreciation and Amortization
Depreciation and amortization	$ 455	$ 547	$ 904	$ 1,117