Leases Leases (Details) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 25, 2019 USD ($)	Sep. 25, 2019 USD ($)	Dec. 27, 2018 USD ($)	Dec. 26, 2018 USD ($)
Lessee, Lease, Description [Line Items]
Finance Lease, Liability, Payments, Remainder of Fiscal Year	$ 14	$ 14
Capital Leases, Future Minimum Payments Due, Next Twelve Months				$ 95
Operating Lease, Payments		19,789
Property held under operating leases, net (ROU Asset)	198,659	198,659	$ 205,223	0
Operating Lease, Cost	6,847	20,688
Short-term Lease, Cost	9	26
Variable Lease, Cost	159	482
Sublease Income	(722)	(1,623)
Lease, Cost	6,302	19,606
Operating Lease, Liability	216,753	216,753	222,283
Finance Lease, Principal Payments		61
Right-of-Use Asset Obtained in Exchange for Operating Lease Liability		8,868
Operating Leases, Future Minimum Payments Due, Next Twelve Months	8,935	8,935		25,388
Operating Leases, Future Minimum Payments Due, Future Minimum Sublease Rentals, Next Twelve Months	651	651		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	24,619	24,619		24,437
Operating Leases, Future Minimum Payments Due, Future Minimum Sublease Rentals, within Two Years	2,612	2,612		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	26,616	26,616		23,342
Operating Leases, Future Minimum Payments Due, Future Minimum Sublease Rentals, within Three Years	2,635	2,635		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	25,569	25,569		22,338
Operating Leases, Future Minimum Payments Due, Future Minimum Sublease Rentals, within Four Years	2,537	2,537		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	23,023	23,023		20,634
Operating Leases, Future Minimum Payments Due, Future Minimum Sublease Rentals, within Five Years	2,558	2,558		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	157,549	157,549		150,342
Operating Leases, Future Minimum Payments Due, Future Minimum Sublease Rentals, Thereafter	19,394	19,394		2,612
Finance Lease, Liability, Payments, Due	167	167
Capital Leases, Future Minimum Payments Due				248
Operating Leases, Future Minimum Payments Due	266,311	266,311		266,481
Operating Leases, Future Minimum Payments Due, Future Minimum Sublease Rentals	30,387	30,387		8,231
Finance Lease, Liability, Undiscounted Excess Amount	(43)	(43)
Lessee, Operating Lease, Liability, Undiscounted Excess Amount	(49,558)	(49,558)
Finance Lease, Liability	124	124
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	(32)	(32)		(68)
Obligations under finance leases, net of current portion	92	92		116
Finance Lease, Liability, Current	(32)	(32)
Current portion of obligations under operating leases	(17,904)	(17,904)		0
Finance Lease, Liability, Noncurrent	92	92
Finance Lease, Right-of-Use Asset, Amortization	0	9
Finance Lease, Interest Expense	9	24
Operating Lease, Liability, Noncurrent	$ 198,849	$ 198,849		$ 0
Number Of Finance Leases	1	1
Number of Restaurants with lease modification	3	6
Operating Lease, Lease Income	$ 100	$ 400
Property Lease [Member]
Lessee, Lease, Description [Line Items]
Operating Lease, Payments		18,819
Operating Lease, Cost	6,534	19,721
Short-term Lease, Cost	0	0
Variable Lease, Cost	121	346
Sublease Income	(722)	(1,623)
Lease, Cost	$ 5,942	18,477
Finance Lease, Principal Payments		61
Right-of-Use Asset Obtained in Exchange for Operating Lease Liability		$ 8,832
Finance Lease, Weighted Average Remaining Lease Term	3 years 29 days	3 years 29 days
Operating Lease, Weighted Average Discount Rate, Percent	4.40%	4.40%
Operating Lease, Weighted Average Remaining Lease Term	12 years 2 months 14 days	12 years 2 months 14 days
Finance Lease, Weighted Average Discount Rate, Percent	11.10%	11.10%
Finance Lease, Right-of-Use Asset, Amortization	$ 0	$ 9
Finance Lease, Interest Expense	9	$ 24
Lease Not Yet Commenced [Member]
Lessee, Lease, Description [Line Items]
Number Of Leases		0
Property Lease [Member]
Lessee, Lease, Description [Line Items]
Right-of-Use Asset Obtained in Exchange for Operating Lease Liability	2,000	$ 3,300
Equipment Lease [Member]
Lessee, Lease, Description [Line Items]
Operating Lease, Payments		970
Operating Lease, Cost	313	967
Short-term Lease, Cost	9	26
Variable Lease, Cost	38	136
Sublease Income	0	0
Lease, Cost	$ 360	1,129
Finance Lease, Principal Payments		0
Right-of-Use Asset Obtained in Exchange for Operating Lease Liability		$ 36
Operating Lease, Weighted Average Discount Rate, Percent	4.00%	4.00%
Operating Lease, Weighted Average Remaining Lease Term	3 years 1 month	3 years 1 month
Finance Lease, Weighted Average Discount Rate, Percent	0.00%	0.00%
Operating Expense [Member]
Lessee, Lease, Description [Line Items]
Lease, Cost	$ 6,015	$ 18,675
General and Administrative Expense [Member]
Lessee, Lease, Description [Line Items]
Lease, Cost	116	348
Depreciation and amortization [Member]
Lessee, Lease, Description [Line Items]
Lease, Cost	0	9
Interest Expense [Member]
Lessee, Lease, Description [Line Items]
Lease, Cost	9	24
Restructuring Charges [Member]
Lessee, Lease, Description [Line Items]
Lease, Cost	$ 162	$ 550
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
Minimum [Member]
Lessee, Lease, Description [Line Items]
Lessor, Operating Lease, Term of Contract	3 years	3 years
Maximum [Member]
Lessee, Lease, Description [Line Items]
Lessor, Operating Lease, Term of Contract	20 years	20 years