Discontinued Operations (Summary Of Results) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Oct. 02, 2016	Jul. 03, 2016	Apr. 03, 2016	Dec. 31, 2015	Oct. 04, 2015	Jul. 05, 2015	Apr. 05, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Net sales	$ 131,914	$ 74,533	$ 69,516	$ 65,942	$ 115,744	$ 72,325	$ 84,609	$ 82,971	$ 341,905	$ 355,649	$ 347,198
Cost of sales									(256,243)	(266,216)	(265,892)
Selling and general expenses									(22,429)	(21,735)	(21,422)
Other income (expense)									810	397	367
Earnings (loss) from discontinued operations, net of tax	$ 1,073	$ 537	$ 338	$ 701	$ (914)	$ (46)	$ (516)	$ (190)	2,649	(1,666)	(4,275)
Discontinued Operations Held-for-sale [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Net sales									76,555	72,041	65,165
Cost of sales									(70,848)	(71,897)	(69,270)
Selling and general expenses									(2,618)	(2,275)	(1,794)
Other income (expense)									976	(1)	(1)
Earnings (loss) from discontinued operations before provision for income taxes									4,065	(2,132)	(5,900)
Provision for (benefit from) income taxes from discontinued operations									1,416	(466)	(1,625)
Earnings (loss) from discontinued operations, net of tax									$ 2,649	$ (1,666)	$ (4,275)