Employee Benefit Plans (Defined Contribution Plans) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 27, 2021	Mar. 28, 2020
Non-Collective-Bargaining Plan [Member]
Defined Contribution Plans [Line Items]
Percentage of Employees Covered	85.00%
Employer Matching Contribution, Percentage	1.00%
Employer Matching Contribution, Discretionary Percentage	2.00%
Maximum Annual Contribution Per Employee, Percentage	3.00%
Cost Recognized	$ 224	$ 106
Collective-Bargaining Plan [Member]
Defined Contribution Plans [Line Items]
Percentage of Employees Covered	15.00%
Maximum Annual Contribution Per Employee, Percentage	2.75%
Cost Recognized	$ 21	$ 26