Reorganization and Realignment Costs G&A Realignment - May 2017 Plan Accrual Rollforward (Details) - G&A Realignment – May 2017 Plan - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jul. 01, 2018	Jun. 30, 2019	Jul. 01, 2018
Restructuring Cost and Reserve
Beginning balance			$ 7,324	$ 12,270
Charges	$ 2,683	$ 2,016	3,285	4,551
Payments for Restructuring			(5,167)	(6,729)
Ending balance	5,442	10,092	5,442	10,092
Severance and related employee costs
Restructuring Cost and Reserve
Beginning balance			7,241	12,093
Charges	2,130	1,052	2,602	3,111
Payments for Restructuring			(4,724)	(5,326)
Ending balance	5,119	9,878	5,119	9,878
Recruitment and relocation
Restructuring Cost and Reserve
Beginning balance			83	177
Charges	482	360	596	508
Payments for Restructuring			(356)	(471)
Ending balance	323	214	323	214
Other Restructuring
Restructuring Cost and Reserve
Beginning balance			0	0
Charges	71	604	87	932
Payments for Restructuring			(87)	(932)
Ending balance	0	0	0	0
Accrued expenses and other current liabilities
Restructuring Cost and Reserve
Ending balance	4,835	7,985	4,835	7,985
Other Liabilities
Restructuring Cost and Reserve
Ending balance	$ 607	$ 2,107	$ 607	$ 2,107