Restructuring (Narrative) (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jul. 01, 2017	Jun. 30, 2018	Jul. 01, 2017	Jun. 30, 2017
Restructuring Cost and Reserve [Line Items]
Restructuring charges	$ 4,376,000	$ 1,576,000	$ 5,405,000	$ 1,642,000
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	9,300,000		9,300,000
Restructuring charges	300,000	2,400,000	1,300,000	2,400,000
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	(500,000)	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	$ (400,000)	0	$ (100,000)
Minimum | June 2017 Plan
Restructuring Cost and Reserve [Line Items]
Restructuring and related cost, expected cost	8,000,000		8,000,000
Maximum | June 2017 Plan
Restructuring Cost and Reserve [Line Items]
Restructuring and related cost, expected cost	$ 12,000,000		$ 12,000,000
Disposed of by Sale | Hyderabad
Restructuring Cost and Reserve [Line Items]
Ownership percentage					100.00%