Employee Benefit Plans (Benefits Expected to be Paid in Future Years) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 27, 2017	Dec. 28, 2016
Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Employer contributions	$ 0	$ 9,546
Other Defined Benefit Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Employer contributions	286	$ 194
Estimated employer contributions during 2018	300
Benefits expected to be paid:
2018	280
2019	564
2020	253
2021	229
2022	296
2023 through 2027	$ 1,027