Leases Leases (Details) $ in Thousands	3 Months Ended
	Mar. 25, 2020 USD ($)	Mar. 27, 2019 USD ($)	Dec. 25, 2019 USD ($)	Dec. 27, 2018 USD ($)
Lessee, Lease, Description [Line Items]
Finance Lease, Liability, to be Paid, Remainder of Fiscal Year	$ 41
Capital Leases, Future Minimum Payments Due, Next Twelve Months			$ 54
Operating Lease, Payments	6,569
Property held under operating leases, net (ROU asset)	187,610		192,395	$ 205,223
Operating Lease, Cost	6,854
Short-term Lease, Cost	2
Variable Lease, Cost	118
Sublease Income	(778)
Lease, Cost	6,202
Operating Lease, Liability	210,007		213,898	222,283
Finance Lease, Principal Payments	8
Right-of-Use Asset Obtained in Exchange for Operating Lease Liability	319
Operating Leases, Future Minimum Payments Due, Next Twelve Months	20,080		26,808
Operating Leases, Future Minimum Payments Due, Future Minimum Sublease Rentals, Next Twelve Months	2,103		2,754
Finance Lease, Liability, to be Paid, Year Two	54
Capital Leases, Future Minimum Payments Due in Two Years			54
Operating Leases, Future Minimum Payments, Due in Two Years	26,702		25,978
Operating Leases, Future Minimum Payments Due, Future Minimum Sublease Rentals, within Two Years	2,887		2,887
Finance Lease, Liability, to be Paid, Year Three	45
Capital Leases, Future Minimum Payments Due in Three Years			45
Operating Leases, Future Minimum Payments, Due in Three Years	25,694		24,871
Operating Leases, Future Minimum Payments Due, Future Minimum Sublease Rentals, within Three Years	3,284		3,284
Finance Lease, Liability, to be Paid, Year Four	0
Capital Leases, Future Minimum Payments Due in Four Years			0
Operating Leases, Future Minimum Payments, Due in Four Years	23,289		22,309
Operating Leases, Future Minimum Payments Due, Future Minimum Sublease Rentals, within Four Years	3,318		3,318
Finance Lease, Liability, to be Paid, Year Five	0
Capital Leases, Future Minimum Payments Due in Five Years			0
Operating Leases, Future Minimum Payments, Due in Five Years	21,018		19,751
Operating Leases, Future Minimum Payments Due, Future Minimum Sublease Rentals, within Five Years	3,203		3,203
Finance Lease, Liability, to be Paid, after Year Five	0
Capital Leases, Future Minimum Payments Due Thereafter			0
Operating Leases, Future Minimum Payments, Due Thereafter	141,124		139,454
Operating Leases, Future Minimum Payments Due, Future Minimum Sublease Rentals, Thereafter	27,265		27,265
Finance Lease, Liability, Payment, Due	140
Capital Leases, Future Minimum Payments Due			153
Operating Leases, Future Minimum Payments Due	257,907		259,171
Operating Leases, Future Minimum Payments Due, Future Minimum Sublease Rentals	42,060		42,711
Finance Lease, Liability, Undiscounted Excess Amount	(31)
Lessee, Operating Lease, Liability, Undiscounted Excess Amount	(47,900)		(45,273)
Finance Lease, Liability	109
Capital Leases, Future Minimum Payments, Interest Included in Payments			(36)
Capital Leases, Future Minimum Payments, Present Value of Net Minimum Payments			117
Capital Lease Obligations, Current	(36)		(34)
Obligations under finance leases, net of current portion	73		83
Finance Lease, Liability, Current	(36)
Current portion of obligations under operating leases	(17,585)		(16,406)
Finance Lease, Liability, Noncurrent	73
Finance Lease, Interest Expense	6
Operating Lease, Liability, Noncurrent	$ 192,422		$ 197,492
Number Of Finance Leases	1
Number of Restaurants with lease modification	3
Operating Lease, Lease Income	$ 100	$ 128
Operating Lease, Impairment Loss	(543)
Impairment of Right-of-Use Assets	543
Operating Expense [Member]
Lessee, Lease, Description [Line Items]
Lease, Cost	5,879
General and Administrative Expense [Member]
Lessee, Lease, Description [Line Items]
Lease, Cost	111
Interest Expense [Member]
Lessee, Lease, Description [Line Items]
Lease, Cost	6
Restructuring Charges [Member]
Lessee, Lease, Description [Line Items]
Lease, Cost	$ 206
Minimum [Member]
Lessee, Lease, Description [Line Items]
Lessor, Operating Lease, Term of Contract	3 years
Capital Leases of Lessee, Contingent Rentals, Basis Spread on Variable Rate	2.38%		3.96%
Maximum [Member]
Lessee, Lease, Description [Line Items]
Lessor, Operating Lease, Term of Contract	20 years
Capital Leases of Lessee, Contingent Rentals, Basis Spread on Variable Rate	11.10%		11.10%
Property lease modification [Member]
Lessee, Lease, Description [Line Items]
Right-of-Use Asset Obtained in Exchange for Operating Lease Liability	$ 300
Property Lease [Member]
Lessee, Lease, Description [Line Items]
Operating Lease, Payments	6,260
Operating Lease, Cost	6,530
Short-term Lease, Cost	0
Variable Lease, Cost	104
Sublease Income	(778)
Lease, Cost	5,862
Finance Lease, Principal Payments	8
Right-of-Use Asset Obtained in Exchange for Operating Lease Liability	$ 307
Finance Lease, Weighted Average Remaining Lease Term	2 years 7 months
Operating Lease, Weighted Average Discount Rate, Percent	4.35%
Operating Lease, Weighted Average Remaining Lease Term	11 years 11 months 10 days
Finance Lease, Weighted Average Discount Rate, Percent	11.10%
Finance Lease, Interest Expense	$ 6
Operating Lease, Impairment Loss	(543)
Property Lease [Member] | Accounting Standards Update 2016-02 [Member]
Lessee, Lease, Description [Line Items]
Property held under operating leases, net (ROU asset)				200,555
Operating Lease, Liability				217,615
Equipment Lease [Member]
Lessee, Lease, Description [Line Items]
Operating Lease, Payments	309
Operating Lease, Cost	324
Short-term Lease, Cost	2
Variable Lease, Cost	14
Sublease Income	0
Lease, Cost	340
Finance Lease, Principal Payments	0
Right-of-Use Asset Obtained in Exchange for Operating Lease Liability	$ 12
Operating Lease, Weighted Average Discount Rate, Percent	3.95%
Operating Lease, Weighted Average Remaining Lease Term	2 years 11 months 20 days
Finance Lease, Weighted Average Discount Rate, Percent	0.00%
Operating Lease, Impairment Loss	$ 0
Equipment Lease [Member] | Accounting Standards Update 2016-02 [Member]
Lessee, Lease, Description [Line Items]
Property held under operating leases, net (ROU asset)				4,668
Operating Lease, Liability				$ 4,668
Lease Not Yet Commenced [Member]
Lessee, Lease, Description [Line Items]
Number Of Leases	1