Summary of Significant Accounting Policies (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 30, 2018	Sep. 30, 2018	Jul. 01, 2018	Apr. 01, 2018	Dec. 31, 2017	Sep. 24, 2017	Jun. 25, 2017	Mar. 26, 2017	Dec. 30, 2018	Dec. 31, 2017	Dec. 25, 2016	Jan. 01, 2018
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Tax Cuts and Jobs Act of 2017, Incomplete Accounting, Provisional Income Tax Expense (Benefit)	$ 1,900
Tax Act, additional income tax expense					$ 68,700					$ 68,700
Self insurance reserve	35,000				38,000				$ 35,000	38,000
Net cash provided by/(used in) operating activities									(157,117)	(86,712)	$ (103,876)
Net cash provided by (used in) financing activities									3,824	(26,019)	(237,024)
Change in restricted cash									101,095	(14,100)	(124,468)
Adjustment to opening retained earnings	1,506,004				1,310,136				1,506,004	1,310,136
Operating Income (Loss)	74,667	$ 41,443	$ 40,002	$ 34,055	90,480	$ 31,820	$ 26,476	$ 27,815	190,167	176,591	112,678
Contract with Customer Asset Net	2,500								2,500
Accounting Standards Update 2018-02
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Tax Cuts and Jobs Act of 2017, Reclassification from AOCI to Retained Earnings, Tax Effect									$ 94,100
Accounting Standards Update 2017-07 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Income from Production Costs, Reclassified to Other Components of Net Periodic Benefit Costs/(Income)										900	1,300
Income from Selling and General and Administrative Costs, Reclassified to Other Components of Net Periodic Benefit Costs/(Income)										4,200	7,200
Restructuring charges reclassified into other components of net periodic benefit costs											1,700
Pension settlement charges reclassified into other components of net periodic benefit costs											21,300
Gain related to settlement of contractual funding										32,700
Lump-sum Payments for Pension Settlement										102,100
Operating Costs and Expenses										5,100	8,500
Operating Income (Loss)										64,200	$ 11,100
Accounting Standards Update 2014-09 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Contract with Customer Asset Net												$ 3,500
Contract with Customer, Asset, Net, Current												1,300
Contract with Customer, Asset, Net, Noncurrent												2,200
Maximum [Member] | Building and Building Improvements [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Property, plant and equipment, useful life									40 years
Maximum [Member] | Equipment [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Property, plant and equipment, useful life									30 years
Maximum [Member] | Computer Software, Intangible Asset [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Property, plant and equipment, useful life									5 years
Minimum [Member] | Building and Building Improvements [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Property, plant and equipment, useful life									10 years
Minimum [Member] | Equipment [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Property, plant and equipment, useful life									3 years
Minimum [Member] | Computer Software, Intangible Asset [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Property, plant and equipment, useful life									2 years
Letter of Credit [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Securities pledged as collateral	54,200				$ 63,000				$ 54,200	$ 63,000
Difference between Revenue Guidance in Effect before and after Topic 606 [Member] | Accounting Standards Update 2014-09 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Adjustment to opening retained earnings												2,600
Retained Earnings (Accumulated Deficit), Before Tax												$ 3,500
Scenario, Forecast [Member] | Accounting Standards Update 2014-09 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Increase (Decrease) in Other Revenue									1,300
Pro Forma [Member] | Maximum [Member] | Accounting Standards Update 2016-02 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating Lease, Right-of-Use Asset	40,000								40,000
Operating Lease, Liability	40,000								40,000
Pro Forma [Member] | Minimum [Member] | Accounting Standards Update 2016-02 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating Lease, Right-of-Use Asset	35,000								35,000
Operating Lease, Liability	$ 35,000								$ 35,000