Restructuring (Schedule of Restructuring Activities) (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 29, 2018	Sep. 30, 2017
Restructuring Reserve [Roll Forward]
Balance at beginning of the period	$ 2,447	$ 1,874
Restructuring charges	5,495	4,713
Costs paid or otherwise settled	(6,497)	(4,086)
Balance at the end of the period	1,445	2,501
Severance & related
Restructuring Reserve [Roll Forward]
Balance at beginning of the period	1,192	801
Restructuring charges	4,034	2,433
Costs paid or otherwise settled	(4,662)	(1,707)
Balance at the end of the period	564	1,527
Lease Termination & Fixed Assets
Restructuring Reserve [Roll Forward]
Balance at beginning of the period	870	1,036
Restructuring charges	437	816
Costs paid or otherwise settled	(667)	(897)
Balance at the end of the period	640	955
Software Contracts & Engineering Tools
Restructuring Reserve [Roll Forward]
Balance at beginning of the period	360	25
Restructuring charges	913	686
Costs paid or otherwise settled	(1,055)	(711)
Balance at the end of the period	218	0
Other
Restructuring Reserve [Roll Forward]
Balance at beginning of the period	25	12
Restructuring charges	111	778
Costs paid or otherwise settled	(113)	(771)
Balance at the end of the period	$ 23	$ 19