Employee Benefit Plans (Amounts Recognized in the Consolidated Balance Sheets) (Details) - USD ($) $ in Thousands	Dec. 27, 2017	Dec. 28, 2016
Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Other current liabilities	$ 0	$ 0
Other noncurrent liabilities	0	0
Net amount recognized	0	0
Other Defined Benefit Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Other current liabilities	(280)	(259)
Other noncurrent liabilities	(2,328)	(2,380)
Net amount recognized	$ (2,608)	$ (2,639)