Restructuring Costs (Details) - USD ($) $ in Thousands	3 Months Ended
	Apr. 01, 2018	Apr. 02, 2017
Restructuring Reserve [Roll Forward]
Restructuring reserve, beginning balance	$ 284	$ 2,473
Restructuring charges	0	293
Cash payments	133	470
Restructuring reserve, ending balance	151	2,296
Severance
Restructuring Reserve [Roll Forward]
Restructuring charges		293
2016 Plan
Restructuring Reserve [Roll Forward]
Restructuring reserve, beginning balance	90
Cash payments	90
Restructuring reserve, ending balance	0
2015 Plan
Restructuring Reserve [Roll Forward]
Restructuring reserve, beginning balance		1,300
Cash payments		367
Restructuring reserve, ending balance		1,204
2015 Plan | Severance
Restructuring Reserve [Roll Forward]
Restructuring charges		271
2014 Plan
Restructuring Reserve [Roll Forward]
Restructuring reserve, beginning balance		282
Cash payments		76
Restructuring reserve, ending balance		228
2014 Plan | Severance
Restructuring Reserve [Roll Forward]
Restructuring charges		22
2013 Plan
Restructuring Reserve [Roll Forward]
Restructuring reserve, beginning balance		426
Cash payments		0
Restructuring reserve, ending balance		426
2013 Plan | Severance
Restructuring Reserve [Roll Forward]
Restructuring charges		0
2012 and Prior Plans
Restructuring Reserve [Roll Forward]
Restructuring reserve, beginning balance	194	465
Cash payments	43	27
Restructuring reserve, ending balance	$ 151	438
2012 and Prior Plans | Severance
Restructuring Reserve [Roll Forward]
Restructuring charges		$ 0