Restructuring (Schedule of Restructuring Activities) (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2017	Oct. 01, 2016
Restructuring Reserve [Roll Forward]
Balance at beginning of the period	$ 1,874	$ 5,078
Restructuring charges	4,713	8,316
Costs paid or otherwise settled	(4,086)	(11,280)
Balance at the end of the period	2,501	2,114
Severance & related
Restructuring Reserve [Roll Forward]
Balance at beginning of the period	801	3,696
Restructuring charges	2,433	1,863
Costs paid or otherwise settled	(1,707)	(4,688)
Balance at the end of the period	1,527	871
Lease Termination
Restructuring Reserve [Roll Forward]
Balance at beginning of the period	1,036	1,005
Restructuring charges	816	2,343
Costs paid or otherwise settled	(897)	(2,315)
Balance at the end of the period	955	1,033
Software Contracts & Engineering Tools
Restructuring Reserve [Roll Forward]
Balance at beginning of the period	25	377
Restructuring charges	686	1,917
Costs paid or otherwise settled	(711)	(2,211)
Balance at the end of the period	0	83
Other
Restructuring Reserve [Roll Forward]
Balance at beginning of the period	12	0
Restructuring charges	778	2,193
Costs paid or otherwise settled	(771)	(2,066)
Balance at the end of the period	$ 19	$ 127