Summary of Significant Accounting Policies - Additional Information (Details)				2 Months Ended	12 Months Ended
	Jul. 13, 2018 USD ($)	Jul. 30, 2014	Jul. 11, 2014 restaurant	Mar. 06, 2020 USD ($)	Dec. 25, 2019 USD ($) restaurant supplier franchisee	Dec. 26, 2018 USD ($) restaurant supplier	Dec. 27, 2017 USD ($) restaurant	Sep. 25, 2019 restaurant	Jun. 26, 2019 restaurant	Mar. 27, 2019 restaurant	Sep. 26, 2018 restaurant	Jun. 27, 2018 restaurant	Mar. 28, 2018 restaurant	Dec. 28, 2017 USD ($)	Dec. 28, 2016 USD ($)
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Unrecognized Tax Benefits, Income Tax Penalties Accrued					$ 0	$ 0	$ 0
Lessee, Operating Lease, Term of Contract					20 years
Proceeds from disposition of restaurants					$ 4,770,000	0	0
Gain (Loss) on Disposition of Business					(5,058,000)	0	0
Revolver loan					97,000,000	74,000,000
Cash available					$ 8,070,000	$ 6,969,000	8,550,000								$ 2,168,000
Number of restaurants closed | restaurant					1	7
Capitalized internal cost					$ 1,100,000	$ 1,300,000	1,900,000
Capitalized internal interest cost					100,000	200,000	200,000
Asset impairment charges					$ 3,559,000	$ 5,147,000	32,594,000
Number of Restaurants Sold | restaurant					4
Number of restaurants | restaurant					4	4
Transaction costs	$ 800,000
Amortization expense for deferred financing costs					$ 251,000	$ 280,000	304,000
Accrued insurance					9,440,000	7,076,000
Expense for payroll and benefits reserves					9,600,000	8,000,000	6,800,000
Promotional allowances amount					8,000,000	8,800,000	8,900,000
Revenue allocated to loyalty points not redeemed					$ 1,100,000	1,000,000
Loyalty rewards program, expected loyalty points redemption period					1 year
Advertising expense					$ 16,100,000	16,098,347	15,500,000
Accrued advertising					500,000	300,000
Advertising cost included in accounts receivable and current assets					0
Recovery of securities lawsuits related legal expenses					10,000,000	8,356,000	1,666,000
Unrecognized tax benefits, accrual of interest or penalties					0	0
Unrecognized tax benefits, interest or penalties expenses					0	0	0
Percentage of cash savings in taxes realized as a result of utilizing net operating losses payable to pre-IPO stockholders		85.00%
Charge relating to present value of total expected TRA payments					8,200,000	13,900,000
Payments to pre-IPO stockholders under TRA					5,764,000	$ 7,272,000	$ 11,109,000
Impairment of assets					$ 3,600,000
Number of restaurants that failed impairment testing | restaurant					1	4	23
Number of commitments to open franchised restaurants | restaurant					44
Operating lease obligations					$ 259,171,000	$ 266,481,000
Closed-store reserves					$ 0	$ 4,503,000	$ 1,051,000
Minimum
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Percentage of monthly franchise fee					4.00%
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Explanation					10 years
Maximum
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Percentage of monthly franchise fee					5.00%
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Explanation					20 years
Franchised
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Number of restaurants | restaurant					287	271		284	284	273	271	269	268
Advertising fees					$ 22,400,000	$ 21,200,000	20,500,000
Interest Expense
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Amortization expense for deferred financing costs					300,000	280,240	304,235
General and Administrative Expense
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Abandoned site and other site selection costs					100,000	300,000	500,000
Preopening costs					400,000	800,000	$ 2,000,000
closed store [Member]
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Operating Lease, Expense					1,300,000
Other Assets
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Deferred financing fees net of accumulated amortization					$ 800,000	$ 1,100,000
Supplier Concentration Risk
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Number Of Suppliers | supplier					1	1
Revenue | Geographic Concentration Risk
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Percentage of concentration					100.00%	100.00%
Accounts Receivable
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Percentage of concentration					10.00%	40.00%
Number of Franchisees					1	2
Supplier One | Accounts Payable | Supplier Concentration Risk
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Percentage of concentration					11.70%
Supplier Two | Accounts Payable | Supplier Concentration Risk
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Percentage of concentration						36.00%
Largest Supplier One | Purchased | Supplier Concentration Risk
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Percentage of concentration					29.00%	28.80%	29.30%
Texas
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Number of restaurants closed | restaurant					2	2	4
Asset impairment charges						$ 27,700,000
Number of Restaurants Sold | restaurant					5
CALIFORNIA
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Number of restaurants closed | restaurant					2
Number of Restaurants Sold | restaurant					4
Number of restaurants					4
Greater Los Angeles area market | Franchised
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Number of restaurants | restaurant					136
Greater Los Angeles area market | Revenue | Geographic Concentration Risk
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Percentage of concentration					70.50%	69.20%	72.90%
Phoenix [Member]
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Number of Restaurants Sold | restaurant					7
Franchise Development Initial Option Agreement | Limited Liability Company
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Number of restaurants | restaurant			15
Number of years available under plan			5 years
Franchise Development Additional Option Agreement | Limited Liability Company
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Number of restaurants | restaurant			100
Number of years available under plan			10 years
Franchise Development Agreement | Limited Liability Company
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Related party agreement, termination period			10 years
2018 Credit Agreement
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Amount of borrowings available					$ 44,600,000
Accounting Standards Update 2014-09
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Cumulative effect of adjustment resulted in an increase in accumulated deficit						$ (3,467,000)
Retained Earnings | Accounting Standards Update 2014-09
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Cumulative effect of adjustment resulted in an increase in accumulated deficit						(3,467,000)								$ 3,500,000
Subsequent Event
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Loss Contingency Accrual, Payments				$ 16,300,000
Subsequent Event | 2018 Credit Agreement
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Prepayment for long-term line of credit				$ 10,000,000
Fair Value, Measurements, Nonrecurring
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Impairment of assets					$ 339,000	$ 5,147,000	$ 32,594,000
Impaired Long-Lived Assets Held and Used, Asset Name [Domain]
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Number of restaurants | restaurant					1
Hardware Services [Member]
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Revenue, Remaining Performance Obligation, Amount					$ 0
Franchise Rights [Member]
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Finite-Lived Intangible Asset, Useful Life					20 years
Finite-Lived Intangible Asset, Useful Life Renewal Period					20 years