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Summary of Significant Accounting Policies (Narrative) (Details) $ in Thousands			3 Months Ended								12 Months Ended
	Dec. 25, 2019 USD ($)	Dec. 26, 2018 USD ($)	Dec. 25, 2019 USD ($)	Sep. 25, 2019 USD ($)	Jun. 26, 2019 USD ($)	Mar. 27, 2019 USD ($)	Dec. 26, 2018 USD ($)	Sep. 26, 2018 USD ($)	Jun. 27, 2018 USD ($)	Mar. 28, 2018 USD ($)	Dec. 25, 2019 USD ($) segment	Dec. 26, 2018 USD ($)	Dec. 27, 2017 USD ($)	Dec. 27, 2018 USD ($)	Dec. 28, 2017 USD ($)	Dec. 29, 2016 USD ($)
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Advertising expense											$ 11,200	$ 15,000	$ 14,300
Revenue			$ 113,836	$ 124,258	$ 151,884	$ 151,411	$ 159,549	$ 158,023	$ 157,334	$ 155,273	541,389	630,179	529,169
Discounted insurance liabilities	$ 16,100	$ 17,000	$ 16,100				$ 17,000				$ 16,100	$ 17,000
Self insurance liabilities, discount rate	2.00%	2.50%	2.00%				2.50%				2.00%	2.50%
Undiscounted insurance liabilities	$ 16,900	$ 18,200
Number of operating segments \| segment											1
Operating lease liabilities	169,094		$ 169,094								$ 169,094			$ 101,300
Operating lease ROU assets	$ 158,550		158,550								158,550			94,200
Cumulative effect adjustment														(394)	$ (15,446)	$ 9,139
(Deficit)
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect adjustment														(400)
Deferred Tax Asset
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect adjustment														$ 100
Estimated Forfeitures \| (Deficit)
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect adjustment																(400)
Estimated Forfeitures \| Other Noncurrent Assets
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect adjustment																(200)
Estimated Forfeitures \| Additional Paid-in Capital
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect adjustment																600
Excess Tax Benefits \| (Deficit)
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect adjustment																$ 9,000
Franchise and license revenue
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Advertising expense											81,100	$ 78,300	1,900
Revenue			$ 65,033	$ 60,676	$ 56,437	$ 52,866	$ 55,160	$ 54,414	$ 54,593	$ 54,080	$ 235,012	$ 218,247	$ 138,817