Restructuring (Schedule of Restructuring Activities) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jul. 01, 2017	Jul. 02, 2016	Jul. 01, 2017	Jul. 02, 2016
Restructuring Reserve [Roll Forward]
Balance at beginning of the period			$ 1,874	$ 5,078
Restructuring charges				7,999
Restructuring charges	$ 1,576	$ 2,568	1,642	7,999
Costs paid or otherwise settled			(994)	(9,859)
Balance at the end of the period	2,522	3,218	2,522	3,218
Severance & related
Restructuring Reserve [Roll Forward]
Balance at beginning of the period			801	3,696
Restructuring charges			1,276	1,878
Costs paid or otherwise settled			(52)	(4,406)
Balance at the end of the period	2,025	1,168	2,025	1,168
Lease Termination
Restructuring Reserve [Roll Forward]
Balance at beginning of the period			1,036	1,005
Restructuring charges			57	2,234
Costs paid or otherwise settled			(616)	(1,402)
Balance at the end of the period	477	1,837	477	1,837
Software Contracts & Engineering Tools
Restructuring Reserve [Roll Forward]
Balance at beginning of the period			25	377
Restructuring charges			0	1,931
Costs paid or otherwise settled			(25)	(2,111)
Balance at the end of the period	0	197	0	197
Other
Restructuring Reserve [Roll Forward]
Balance at beginning of the period			12	0
Restructuring charges			309	1,956
Costs paid or otherwise settled			(301)	(1,940)
Balance at the end of the period	$ 20	$ 16	$ 20	$ 16