Leases Leases (Details) $ in Thousands	3 Months Ended	6 Months Ended
	Jun. 26, 2019 USD ($)	Jun. 26, 2019 USD ($)	Dec. 27, 2018 USD ($)	Dec. 26, 2018 USD ($)
Lessee, Lease, Description [Line Items]
Finance Lease, Liability, Payments, Remainder of Fiscal Year	$ 27	$ 27
Capital Leases, Future Minimum Payments Due, Next Twelve Months				$ 95
Operating Lease, Payments		13,015
Property held under operating leases, net (ROU Asset)	199,461	199,461	$ 205,223	0
Operating Lease, Cost	6,912	13,841
Short-term Lease, Cost	9	17
Variable Lease, Cost	154	322
Sublease Income	(511)	(901)
Lease, Cost	6,574	13,303
Operating Lease, Liability	217,339	217,339	222,283
Finance Lease, Principal Payments		53
Right-of-Use Asset Obtained in Exchange for Operating Lease Liability		4,995
Operating Leases, Future Minimum Payments Due, Next Twelve Months	13,263	13,263		25,388
Operating Leases, Future Minimum Payments Due, Future Minimum Sublease Rentals, Next Twelve Months	695	695		1,443
Finance Lease, Liability, Payments, Due Year Two	54	54
Capital Leases, Future Minimum Payments Due in Two Years				54
Operating Leases, Future Minimum Payments, Due in Two Years	26,387	26,387		24,437
Operating Leases, Future Minimum Payments Due, Future Minimum Sublease Rentals, within Two Years	1,108	1,108		1,108
Finance Lease, Liability, Payments, Due Year Three	54	54
Capital Leases, Future Minimum Payments Due in Three Years				54
Operating Leases, Future Minimum Payments, Due in Three Years	26,050	26,050		23,342
Operating Leases, Future Minimum Payments Due, Future Minimum Sublease Rentals, within Three Years	1,078	1,078		1,078
Finance Lease, Liability, Payments, Due Year Four	45	45
Capital Leases, Future Minimum Payments Due in Four Years				45
Operating Leases, Future Minimum Payments, Due in Four Years	25,043	25,043		22,338
Operating Leases, Future Minimum Payments Due, Future Minimum Sublease Rentals, within Four Years	1,001	1,001		1,001
Finance Lease, Liability, Payments, Due Year Five	0	0
Capital Leases, Future Minimum Payments Due in Five Years				0
Operating Leases, Future Minimum Payments, Due in Five Years	22,634	22,634		20,634
Operating Leases, Future Minimum Payments Due, Future Minimum Sublease Rentals, within Five Years	989	989		989
Finance Lease, Liability, Payments, Due after Year Five	0	0
Capital Leases, Future Minimum Payments Due Thereafter				0
Operating Leases, Future Minimum Payments, Due Thereafter	154,940	154,940		150,342
Operating Leases, Future Minimum Payments Due, Future Minimum Sublease Rentals, Thereafter	2,612	2,612		2,612
Finance Lease, Liability, Payments, Due	180	180
Capital Leases, Future Minimum Payments Due				248
Operating Leases, Future Minimum Payments Due	268,317	268,317		266,481
Operating Leases, Future Minimum Payments Due, Future Minimum Sublease Rentals	7,483	7,483		8,231
Finance Lease, Liability, Undiscounted Excess Amount	(49)	(49)
Lessee, Operating Lease, Liability, Undiscounted Excess Amount	(50,978)	(50,978)
Finance Lease, Liability	131	131
Capital Leases, Future Minimum Payments, Interest Included in Payments				(64)
Capital Leases, Future Minimum Payments, Present Value of Net Minimum Payments				184
Capital Lease Obligations, Current	(31)	(31)		(68)
Obligations under finance leases, net of current portion	100	100		116
Finance Lease, Liability, Current	(31)	(31)
Current portion of obligations under operating leases	(18,727)	(18,727)		0
Finance Lease, Liability, Noncurrent	100	100
Finance Lease, Right-of-Use Asset, Amortization	3	9
Finance Lease, Interest Expense	7	15
Operating Lease, Liability, Noncurrent	198,612	$ 198,612		$ 0
Number of Restaurants with lease modification		3
Operating Lease, Lease Income	200	$ 300
Property Lease [Member]
Lessee, Lease, Description [Line Items]
Operating Lease, Payments		12,361
Operating Lease, Cost	6,585	13,187
Short-term Lease, Cost	0	0
Variable Lease, Cost	127	224
Sublease Income	(511)	(901)
Lease, Cost	$ 6,211	12,534
Finance Lease, Principal Payments		53
Right-of-Use Asset Obtained in Exchange for Operating Lease Liability		$ 4,995
Finance Lease, Weighted Average Remaining Lease Term	3 years 3 months 29 days	3 years 3 months 29 days
Operating Lease, Weighted Average Discount Rate, Percent	4.38%	4.38%
Operating Lease, Weighted Average Remaining Lease Term	12 years 2 months 23 days	12 years 2 months 23 days
Finance Lease, Weighted Average Discount Rate, Percent	11.10%	11.10%
Finance Lease, Right-of-Use Asset, Amortization	$ 3	$ 9
Finance Lease, Interest Expense	7	$ 15
Lease Not Yet Commenced [Member]
Lessee, Lease, Description [Line Items]
Number Of Leases		1
Property Lease [Member]
Lessee, Lease, Description [Line Items]
Property held under operating leases, net (ROU Asset)	1,200	$ 1,200
Equipment Lease [Member]
Lessee, Lease, Description [Line Items]
Operating Lease, Payments		654
Operating Lease, Cost	327	654
Short-term Lease, Cost	9	17
Variable Lease, Cost	27	98
Sublease Income	0	0
Lease, Cost	$ 363	769
Finance Lease, Principal Payments		0
Right-of-Use Asset Obtained in Exchange for Operating Lease Liability		$ 0
Operating Lease, Weighted Average Discount Rate, Percent	3.98%	3.98%
Operating Lease, Weighted Average Remaining Lease Term	3 years 6 months 17 days	3 years 6 months 17 days
Finance Lease, Weighted Average Discount Rate, Percent	0.00%	0.00%
Operating Expense [Member]
Lessee, Lease, Description [Line Items]
Lease, Cost	$ 6,256	$ 12,659
General and Administrative Expense [Member]
Lessee, Lease, Description [Line Items]
Lease, Cost	114	233
Depreciation and amortization [Member]
Lessee, Lease, Description [Line Items]
Lease, Cost	3	9
Interest Expense [Member]
Lessee, Lease, Description [Line Items]
Lease, Cost	7	15
Restructuring Charges [Member]
Lessee, Lease, Description [Line Items]
Lease, Cost	$ 194	$ 387
Accounting Standards Update 2016-02 [Member] | Property Lease [Member]
Lessee, Lease, Description [Line Items]
Property held under operating leases, net (ROU Asset)			200,555
Operating Lease, Liability			217,615
Accounting Standards Update 2016-02 [Member] | Equipment Lease [Member]
Lessee, Lease, Description [Line Items]
Property held under operating leases, net (ROU Asset)			4,668
Operating Lease, Liability			$ 4,668