Income Taxes (Reconciliation of Income Taxes) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 27, 2017	Dec. 28, 2016	Dec. 30, 2015	Dec. 28, 2011
Effective tax rate reconciliation [Line Items]
U.S. statutory tax rate	35.00%	35.00%	35.00%
Reconciliation of income taxes at the U.S. federal statutory tax rate to effective tax rate:
U.S. statutory tax rate	35.00%	35.00%	35.00%
State and local taxes, net of federal income tax benefit	5.00%	9.00%	6.00%
Wage addback on income tax credits earned	2.00%	3.00%	2.00%
General business credits generated	(5.00%)	(9.00%)	(6.00%)
Foreign tax credits generated	(2.00%)	(12.00%)	(2.00%)
Pension plan liquidation	0.00%	18.00%	0.00%
Share-based compensation	(3.00%)	(0.00%)	(0.00%)
Impact of tax reform	(3.00%)	(0.00%)	(0.00%)
Other	1.00%	2.00%	(2.00%)
Effective tax rate	30.00%	46.00%	33.00%
Net tax benefit recognized related to the Tax Act	$ 1,600
Tax benefit recognized related to share-based compensation	1,700
Tax benefit recognized with pension plan liquidation		$ 2,100
Pension settlement loss	(21)	(24,297)
Tax benefit recognized with reversal of the valuation allowance	$ (216)	(132)	$ 130	$ 7,200
Tax benefit recognized with foreign tax credits		$ 3,700
Tax Year 2018 [Member]
Effective tax rate reconciliation [Line Items]
U.S. statutory tax rate	21.00%
Reconciliation of income taxes at the U.S. federal statutory tax rate to effective tax rate:
U.S. statutory tax rate	21.00%