Restructuring (Narrative) (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 29, 2018	Sep. 30, 2017	Sep. 29, 2018	Sep. 30, 2017	Jun. 30, 2017
Restructuring Cost and Reserve [Line Items]
Restructuring charges	$ 90,000	$ 3,071,000	$ 5,495,000	$ 4,713,000
June 2018 Plan
Restructuring Cost and Reserve [Line Items]
Restructuring and related cost, cost incurred to date	4,100,000		4,100,000
June 2017 Plan
Restructuring Cost and Reserve [Line Items]
Restructuring and related cost, cost incurred to date	9,400,000		9,400,000
Restructuring charges	100,000	$ 3,100,000	1,400,000	5,500,000
September 2015 Reduction
Restructuring Cost and Reserve [Line Items]
Restructuring and related cost, cost incurred to date	7,200,000		7,200,000
Restructuring charges	0		0	(700,000)
March 2015 Plan
Restructuring Cost and Reserve [Line Items]
Restructuring and related cost, cost incurred to date	20,500,000		20,500,000
Restructuring charges	0		0	$ (100,000)
Minimum | June 2017 Plan
Restructuring Cost and Reserve [Line Items]
Restructuring and related cost, expected cost	21,500,000		21,500,000
Maximum | June 2017 Plan
Restructuring Cost and Reserve [Line Items]
Restructuring and related cost, expected cost	$ 23,000,000		$ 23,000,000
Hyderabad
Restructuring Cost and Reserve [Line Items]
Ownership percentage					100.00%