Consolidated Statements of Shareholders' Equity $ in Thousands	USD ($)	Entity Operated Units restaurant	Common Stock USD ($) shares	Additional Paid-in Capital USD ($)	Accumulated Other Comprehensive Income (Loss) USD ($)	Retained Earnings (Accumulated Deficit) USD ($)
Adjustment for adoption of accounting standards, net of tax	$ 1,912					$ 1,912
Beginning Balance, Shares at Jan. 01, 2019 | shares			37,305,342
Beginning Balance at Jan. 01, 2019	422,274		$ 4	$ 336,941	$ 180	85,149
Net income (loss)	1,425					1,425
Other comprehensive income (loss), net of tax	(118)				(118)
Comprehensive income (loss)	1,307
Stock-based compensation	1,577			1,577
Issuance of vested restricted stock, net of shares withheld for tax withholding, shares | shares			13,172
Issuance of vested restricted stock, net of shares withheld for tax withholding	(84)			(84)
Exercise of stock options, shares | shares			1,500
Exercise of stock options	16			16
Repurchase of common stocks and warrants, shares | shares			(270,874)
Repurchase of common stocks and warrants	(4,306)			(4,306)
Ending Balance, Shares at Mar. 26, 2019 | shares			37,049,140
Ending Balance at Mar. 26, 2019	422,696		$ 4	334,144	62	88,486
Beginning Balance, Shares at Jan. 01, 2019 | shares			37,305,342
Beginning Balance at Jan. 01, 2019	422,274		$ 4	336,941	180	85,149
Net income (loss)	3,517
Other comprehensive income (loss), net of tax	(223)
Comprehensive income (loss)	3,294
Issuance of vested restricted stock, net of shares withheld for tax withholding	(84)
Ending Balance, Shares at Jun. 18, 2019 | shares			36,795,532
Ending Balance at Jun. 18, 2019	423,308		$ 4	332,769	(43)	90,578
Beginning Balance, Shares at Mar. 26, 2019 | shares			37,049,140
Beginning Balance at Mar. 26, 2019	422,696		$ 4	334,144	62	88,486
Net income (loss)	2,092					2,092
Other comprehensive income (loss), net of tax	(105)				(105)
Comprehensive income (loss)	1,987
Stock-based compensation	1,677			1,677
Issuance of vested restricted stock, net of shares withheld for tax withholding, shares | shares			48,499
Exercise of stock options, shares | shares			1,500
Exercise of stock options	15			15
Repurchase of common stocks and warrants, shares | shares			(303,607)
Repurchase of common stocks and warrants	(3,067)			(3,067)
Ending Balance, Shares at Jun. 18, 2019 | shares			36,795,532
Ending Balance at Jun. 18, 2019	423,308		$ 4	332,769	(43)	90,578
Number of restaurants | restaurant		310
Beginning Balance, Shares at Dec. 31, 2019 | shares			37,059,202
Beginning Balance at Dec. 31, 2019	302,107		$ 4	333,379	(52)	(31,224)
Net income (loss)	(102,468)					(102,468)
Other comprehensive income (loss), net of tax	45				45
Comprehensive income (loss)	(102,423)
Stock-based compensation	1,225			1,225
Issuance of vested restricted stock, net of shares withheld for tax withholding, shares | shares			21,758
Issuance of vested restricted stock, net of shares withheld for tax withholding	(105)			(105)
Ending Balance, Shares at Mar. 24, 2020 | shares			37,080,960
Ending Balance at Mar. 24, 2020	200,804		$ 4	334,499	(7)	(133,692)
Beginning Balance, Shares at Dec. 31, 2019 | shares			37,059,202
Beginning Balance at Dec. 31, 2019	302,107		$ 4	333,379	(52)	(31,224)
Net income (loss)	(103,044)
Other comprehensive income (loss), net of tax	52
Comprehensive income (loss)	(102,992)
Issuance of vested restricted stock, net of shares withheld for tax withholding	(105)
Ending Balance, Shares at Jun. 16, 2020 | shares			37,122,976
Ending Balance at Jun. 16, 2020	201,648		$ 4	335,912	0	(134,268)
Beginning Balance, Shares at Mar. 24, 2020 | shares			37,080,960
Beginning Balance at Mar. 24, 2020	200,804		$ 4	334,499	(7)	(133,692)
Net income (loss)	(576)					(576)
Other comprehensive income (loss), net of tax	7				7
Comprehensive income (loss)	(569)
Stock-based compensation	1,413			1,413
Issuance of vested restricted stock, net of shares withheld for tax withholding, shares | shares			42,016
Ending Balance, Shares at Jun. 16, 2020 | shares			37,122,976
Ending Balance at Jun. 16, 2020	$ 201,648		$ 4	$ 335,912	$ 0	$ (134,268)
Number of restaurants | restaurant		294