SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Additional Information (Details)							3 Months Ended	9 Months Ended	12 Months Ended
	Mar. 09, 2023 USD ($)	Jul. 27, 2022 USD ($)	Aug. 04, 2020 USD ($) item	Aug. 03, 2020 USD ($) item	Jul. 30, 2014	Jul. 11, 2014 restaurant	Mar. 30, 2022 USD ($)	Dec. 28, 2022 USD ($) restaurant $ / shares	Dec. 28, 2022 USD ($) restaurant item segment $ / shares	Dec. 29, 2021 USD ($) item	Dec. 30, 2020 USD ($) restaurant	Dec. 29, 2021 $ / shares	Dec. 29, 2021 restaurant	Dec. 29, 2021 item	Dec. 29, 2021
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Total amount of outstanding debt								$ 66,000,000.0	$ 66,000,000.0
Cash available								20,493,000	20,493,000	$ 30,046,000
Leaves of absence and overtime pay due to COVID 19							$ 2,300,000	$ 1,000,000.0	$ 3,300,000	3,900,000	$ 4,900,000
Loyalty Rewards Program, Award Earned			$ 5	$ 10
Loyalty Rewards Program, Points Needed For One Reward | item			50	100
Loyalty Rewards Program, Expiration Period For Inactivity			1 year
Loyalty Reward Program, unused reward expiration period			6 months
Loyalty Rewards Program, Expected Loyalty Points Redemption Period									1 year
Initial lease term								20 years	20 years
Insurance proceeds											100,000
Number of franchised restaurants committed to open | restaurant								72	72
Number of operating segments | segment									1
Bad debt expense											190,000
Revolver loan								$ 66,000,000	$ 66,000,000	40,000,000
Common stock, par value (usd per share) | $ / shares								$ 0.01	$ 0.01			$ 0.01
Gain on recovery of insurance proceeds											$ 2,000,000
Gain on Business Interruption Insurance Recovery, Statement of Income or Comprehensive Income [Extensible Enumeration]											Company Restaurant Expenses
Goodwill and intangible asset impairment									$ 0
Proceeds from swap									600,000
Impairment of property and equipment									481,000	711,000	$ 3,498,000
Accounts payable								$ 12,741,000	12,741,000	10,626,000
Unrecognized tax benefits, accrual of interest or penalties								$ 0	0	0
Interest related to NOPA											100,000
TRA tax expense (benefit)											(100,000)
Percentage of cash savings in taxes realized as a result of utilizing net operating losses payable to pre-IPO stockholders					85.00%
Income tax receivable agreement (income) expense									$ (436,000)	58,000	139,000
AMT Credits, CARES Act											400,000
Proceeds from Income Tax Refunds											500,000
Total deferred amount											4,900,000
Percentage of deferred amount due by current fiscal year															50.00%
Percentage of deferred amount due by next fiscal year								50.00%	50.00%
Percentage of qualified wages paid for refundable payroll tax credit								70.00%	70.00%
Employee retention tax credit										3,400,000
Capitalized internal cost									$ 1,500,000	1,400,000	1,000,000.0
Amortization of deferred financing costs									340,000	251,000	252,000
Expense for payroll and benefits reserves									8,700,000	9,000,000.0	8,400,000
Promotional allowances amount									7,500,000	7,700,000	7,500,000
Advertising expense									16,400,000	16,100,000	15,300,000
Accrued loyalty rewards program liability								$ 500,000	500,000	700,000
Asset impairment charges									500,000		3,500,000
Accrued advertising								800,000	800,000	3,600,000
Accrued insurance								11,120,000	11,120,000	11,193,000
Recovery of securities lawsuits related legal expenses and other insurance claims											(123,000)
Proceeds from disposition of restaurants									1,002,000	4,556,000
Gain (loss) on sale of restaurants									848,000	(1,534,000)
Charge relating to present value of total expected TRA payments								700,000	700,000	1,500,000
Payments to pre-IPO stockholders under TRA									430,000	1,658,000	$ 5,237,000
Operating Lease ROU assets								165,584,000	165,584,000	171,981,000
Employee retention credit receivable								$ 300,000	300,000
Proceeds from employee retention credit									$ 3,100,000
Franchise Rights
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Renewal period									20 years
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, Period								10 years	10 years
Maximum
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
TRA tax expense (benefit)									$ 400,000	100,000
Percentage of monthly franchise fee									5.00%
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period								20 years	20 years
Other Assets
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Deferred financing fees net of accumulated amortization								$ 900,000	$ 900,000	400,000
Franchise Development Initial Option Agreement
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Number of restaurants | restaurant								0	0
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
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Number of years available under plan						10 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						5 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
Closed Or Subleased Restaurant Locations
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Operating Lease ROU assets								$ 30,700,000	$ 30,700,000	$ 21,900,000
Accounts Receivable
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Number of Franchisees | item									1
Supplier Concentration Risk | Accounts Payable
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Number Of Suppliers | item									1	1
Supplier Concentration Risk | Supplier One | Accounts Payable
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Percentage of concentration									41.70%	26.10%
Supplier Concentration Risk | Largest Supplier One | Purchased
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Percentage of concentration									28.50%	27.10%	26.90%
Geographic Concentration Risk | Revenue
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Percentage of concentration									100.00%	100.00%	100.00%
Hardware Services
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Unsatisfied performance obligations								0	$ 0
2018 Credit Agreement | Revolving Credit Facility
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
maximum borrowing capacity		$ 150,000,000.0
Senior secured revolving facility term		5 years
Revolver loan										$ 40,000,000.0
Repayment for long-term line of credit										22,800,000
2018 Credit Agreement | Letter of Credit
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
maximum borrowing capacity		$ 15,000,000.0
2018 Credit Agreement | Swing Line Loans
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
maximum borrowing capacity		15,000,000.0
2022 Credit Agreement | Minimum | SOFR
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Debt instrument basis percentage									1.25%
2022 Credit Agreement | Minimum | Base Rate
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Debt instrument basis percentage									0.25%
2022 Credit Agreement | Maximum | SOFR
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Debt instrument basis percentage									2.25%
2022 Credit Agreement | Maximum | Base Rate
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Debt instrument basis percentage									1.25%
2022 Credit Agreement | Revolving Credit Facility
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Proceeds from Lines of Credit									$ 26,000,000.0
maximum borrowing capacity		$ 150,000,000.0
Senior secured revolving facility term		5 years
Revolver loan								66,000,000.0	66,000,000.0
Repayment for long-term line of credit									$ 20,000,000.0
2022 Credit Agreement | Revolving Credit Facility | Federal Funds Rate
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Debt instrument basis percentage									0.50%
2022 Credit Agreement | Revolving Credit Facility | Subsequent Event
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Revolver loan	$ 58,000,000.0
Repayment for long-term line of credit	$ 8,000,000.0
2022 Credit Agreement | Letter of Credit
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
maximum borrowing capacity								15,000,000.0	$ 15,000,000.0
2022 Credit Agreement | Swing Line Loans
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
maximum borrowing capacity								$ 15,000,000.0	$ 15,000,000.0
Texas
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Number of restaurants with ROU asset impairment charges | restaurant											1		1
Restaurants sold | restaurant											1
Number of restaurants closed | restaurant													1
Asset impairment charges										$ 700,000
California
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Number of restaurants | restaurant								2	2
Number of restaurants with ROU asset impairment charges | restaurant													1
Number of restaurants with long-lived assets impairment charges | restaurant											4		3
Number of restaurants closed													1	1
Greater Los Angeles area market | Geographic Concentration Risk | Revenue
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Percentage of concentration									71.20%	70.90%	71.30%
Sacramento Area | Disposed of by Sale | Restaurant Sales
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Number of restaurants sold | restaurant													8
Proceeds from disposition of restaurants										$ 4,600,000
Gain (loss) on sale of restaurants										(1,500,000)
Orange County | Restaurant Sales
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Number of restaurants sold | restaurant								3	3
Orange County | Disposed of by Sale | Restaurant Sales
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Proceeds from disposition of restaurants									$ 1,000,000.0
Gain (loss) on sale of restaurants									800,000
Interest Expense
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Amortization of deferred financing costs									300,000	300,000	$ 300,000
General and Administrative Expense
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Preopening costs									300,000	300,000	100,000
General and Administrative Expense | Maximum
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Abandoned site and other site selection costs									100,000	100,000	100,000
Closed Store
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Closed-store reserve expense									$ 300,000	400,000	1,200,000
Company-operated
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Number of restaurants | restaurant								188	188
Company-operated | Greater Los Angeles area market
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Number of restaurants | restaurant								138	138
Franchised
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Number of restaurants | restaurant								302	302
Advertising fees									$ 28,500,000	$ 25,900,000	$ 22,600,000
Franchised | Accounts Receivable
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Number of Franchisees | item										1
Franchised | Geographic Concentration Risk | Accounts Receivable
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Percentage of concentration									12.90%	10.60%
Franchised | Greater Los Angeles area market
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Number of restaurants | restaurant								141	141