Discontinued Operations (Summary Of Discontinued Operations) (Details) - USD ($) $ in Thousands	3 Months Ended						12 Months Ended
	Sep. 29, 2019	Jun. 30, 2019	Dec. 31, 2018	Sep. 30, 2018	Jul. 01, 2018	Apr. 01, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Cost of sales							$ (236,585)	$ (247,434)	$ (246,399)
Selling and general expenses							(25,462)	(23,286)	(22,900)
Gain on divestiture, net					$ 0				11,413
Other income (expense)							5,926	4,437	3,581
Earnings from discontinued operations, net of tax	$ 1,677	$ 3	$ (71)	$ 131	$ (1)	$ (8)	1,680	51	9,645
Assets Held For Sale [Member] | Discontinued Operations [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Net Sales									421
Cost of sales								65	(675)
Selling and general expenses									(25)
Gain on divestiture, net									11,413
Other income (expense)							2,126		2,753
Earnings from discontinued operations before provision for income taxes							2,126	65	13,887
Provision for income taxes from discontinued operations							446	14	4,242
Earnings from discontinued operations, net of tax							$ 1,680	$ 51	$ 9,645