Depreciation and Amortization by Reportable Segments (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Oct. 02, 2015	Sep. 26, 2014	Oct. 02, 2015	Sep. 26, 2014
Depreciation and Amortization
Depreciation and amortization	$ 4,703	$ 6,344	$ 14,088	$ 17,495
Laser Products
Depreciation and Amortization
Depreciation and amortization	1,394	1,618	4,373	4,838
Vision Technologies
Depreciation and Amortization
Depreciation and amortization	2,109	3,745	6,449	9,552
Precision Motion
Depreciation and Amortization
Depreciation and amortization	680	444	1,842	1,451
Unallocated Corporate and Shared Services
Depreciation and Amortization
Depreciation and amortization	$ 520	$ 537	$ 1,424	$ 1,654