Depreciation and Amortization by Reportable Segments (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Oct. 02, 2015	Sep. 30, 2016	Oct. 02, 2015
Depreciation and Amortization
Depreciation and amortization	$ 5,164	$ 4,703	$ 15,933	$ 14,088
Photonics
Depreciation and Amortization
Depreciation and amortization	1,820	1,394	5,123	4,373
Vision
Depreciation and Amortization
Depreciation and amortization	2,460	2,109	7,861	6,449
Precision Motion
Depreciation and Amortization
Depreciation and amortization	603	680	1,845	1,842
Unallocated Corporate and Shared Services
Depreciation and Amortization
Depreciation and amortization	$ 281	$ 520	$ 1,104	$ 1,424