Basis of Presentation and Summary of Significant Accounting Policies - Additional Information (Detail)		3 Months Ended			12 Months Ended
	Jul. 30, 2014	Jun. 27, 2018 USD ($)	Mar. 28, 2018 USD ($) restaurant supplier segment	Mar. 29, 2017 USD ($)	Dec. 27, 2017 USD ($) supplier	Apr. 19, 2018	Dec. 28, 2016 USD ($)
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Number of operating segments | segment			1
Number of Restaurants			2
Restricted dividend payments, description			Under the 2014 Revolver, Holdings may not make certain payments such as cash dividends, except that it may, inter alia, (i) pay up to $1.0 million per year to repurchase or redeem qualified equity interests of Holdings held by past or present officers, directors, or employees (or their estates) of the Company upon death, disability, or termination of employment, (ii) pay under its income tax receivable agreement (the “TRA”), and, (iii) so long as no default or event of default has occurred and is continuing, (a) make non-cash repurchases of equity interests in connection with the exercise of stock options by directors and officers, provided that those equity interests represent a portion of the consideration of the exercise price of those stock options, (b) pay up to $2.5 million per year pursuant to stock option plans, employment agreements, or incentive plans, (c) make up to $5.0 million in other restricted payments per year, and (d) make other restricted payments, provided that such payments would not cause, in each case, on a pro forma basis, (x) its lease-adjusted consolidated leverage ratio to equal or exceed 4.25 times and (y) its consolidated fixed charge coverage ratio to be less than 1.75 times.
Total amount of outstanding debt			$ 85,300,000
Cash available			6,203,000	$ 6,652,000	$ 8,550,000		$ 2,168,000
Operating lease obligations			286,500,000
Closed-store reserve			2,819,000	849,000
Unrecognized tax benefits, accrual of interest or penalties			0		0
Unrecognized tax benefits, interest or penalties expenses			0	0
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			(918,000)	227,000
Deferred tax assets			7,078,000		7,167,000
Assets			440,934,000		442,711,000
Other accrued expenses and current liabilities			14,730,000		13,270,000
Liabilities, Current			51,362,000		47,325,000
Other noncurrent liabilities			19,463,000		12,772,000
Liabilities			166,417,000		167,761,000
Accumulated deficit			(99,392,000)		(98,427,000)
Stockholders' Equity Attributable to Parent			274,517,000		274,950,000
Liabilities and Equity			440,934,000		$ 442,711,000
Franchise revenue			6,106,000	6,322,000
Franchise advertising fee revenue			5,097,000	0
Revenues			105,756,000	99,771,000
Franchise expenses			5,832,000	817,000
Costs and Expenses			101,308,000	90,410,000
Operating Income (Loss)			4,448,000	9,361,000
Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest			4,478,000	8,344,000
Net income			2,529,000	4,877,000
Recovery of securities lawsuits related legal expenses			(1,634,000)	$ 0
Calculated under revenue guidanec in effect before topic 606 [Member]
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Deferred tax assets			5,793,000
Assets			439,649,000
Other accrued expenses and current liabilities			14,383,000
Liabilities, Current			51,015,000
Other noncurrent liabilities			15,043,000
Liabilities			161,650,000
Accumulated deficit			(95,910,000)
Stockholders' Equity Attributable to Parent			277,999,000
Liabilities and Equity			439,649,000
Franchise revenue			6,118,000
Franchise advertising fee revenue			0
Revenues			100,671,000
Franchise expenses			735,000
Costs and Expenses			96,211,000
Operating Income (Loss)			4,460,000
Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest			4,490,000
Net income			2,541,000
Accounting Standards Update 2014-09
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Deferred tax assets			1,285,000
Assets			1,285,000
Other accrued expenses and current liabilities			347,000
Liabilities, Current			347,000
Other noncurrent liabilities			4,420,000
Liabilities			4,767,000
Accumulated deficit			(3,482,000)
Stockholders' Equity Attributable to Parent			(3,482,000)
Liabilities and Equity			1,285,000
Franchise revenue			(12,000)
Franchise advertising fee revenue			5,097,000
Revenues			5,085,000
Franchise expenses			5,097,000
Costs and Expenses			5,097,000
Operating Income (Loss)			(12,000)
Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest			(12,000)
Net income			(12,000)
Indefinite-lived Intangible Assets
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Asset impairment charges			$ 0
Supplier Concentration Risk
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Number of suppliers | supplier			1		1
Supplier Concentration Risk | Supplier One [Member] | Accounts Payable
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Percentage of concentration			20.20%		14.00%
Supplier Concentration Risk | Largest Supplier One | Purchased
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Percentage of concentration			28.00%	29.00%
Geographic Concentration Risk | Revenue
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Percentage of concentration			100.00%
Los Angeles [Member] | Geographic Concentration Risk | Revenue
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Percentage of concentration			69.20%	73.00%
Subsequent Event
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Recovery of Securities Class Action Legal Costs		$ 300,000
Subsequent Event | TEXAS
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Closed-store reserve		2,000,000
Subsequent Event | Franchisees [Member]
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Number of Restaurants						1
Subsequent Event | Company Operated Properties [Member]
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Number of Restaurants						2
2014 Revolver | Subsequent Event
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Repayments of Debt		$ 3,000,000
2014 Revolver | Senior Secured Revolving Credit Facility
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Debt Instrument, Periodic Payment			$ 8,000,000	$ 3,000,000
Restrictive covenants, maximum annual repurchase or redemption of qualified entity interests			1,000,000
Restrictive covenants, maximum annual payment for stock option plans, employment agreements and incentive plans			2,500,000
Restrictive covenants, maximum annual payment for other restricted payments			$ 5,000,000
Maximum leverage ratio			4.25
Covenant description, coverage ratio			1.75
Amount of borrowings available			$ 107,300,000
Entity Operated Units
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Number of Restaurants | restaurant			212
Franchised Units
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Number of Restaurants | restaurant			268