Condensed Consolidated Statements of Income - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 24, 2020	Jun. 30, 2021	Jun. 24, 2020
Revenue
Total revenue	$ 121,985	$ 99,604	$ 229,706	$ 204,767
Cost of operations
Food and paper cost	27,882	22,873	52,273	48,435
Labor and related expenses	31,526	25,759	62,258	54,452
Occupancy and other operating expenses	25,336	21,922	49,180	44,031
Company restaurant expenses	84,744	70,554	163,711	146,918
General and administrative expenses	10,523	10,465	20,997	19,796
Franchise expenses	8,161	6,627	15,912	13,538
Depreciation and amortization	3,917	4,168	7,855	8,537
Loss on disposal of assets	85	27	111	127
Recovery of securities lawsuits related legal expenses and other insurance claims		(123)		(123)
Loss on assets held for sale	1,524		1,524
Impairment and closed-store reserves	360	437	924	2,839
Total expenses	109,314	92,155	211,034	191,632
Income (loss) from operations	12,671	7,449	18,672	13,135
Interest expense, net	433	908	950	1,813
Income tax receivable agreement expense (income)	27	290	(50)	170
Income (loss) before provision (benefit) for income taxes	12,211	6,251	17,772	11,152
Provision (benefit) for income taxes	3,393	752	4,990	2,053
Net income (loss)	$ 8,818	$ 5,499	$ 12,782	$ 9,099
Net income (loss) per share
Basic (usd per share)	$ 0.25	$ 0.16	$ 0.36	$ 0.26
Diluted (usd per share)	$ 0.24	$ 0.16	$ 0.35	$ 0.26
Weighted-average shares used in computing net income (loss) per share
Basic (shares)	35,927,781	34,836,410	35,861,493	34,747,785
Diluted (shares)	36,416,686	35,410,198	36,423,394	35,382,607
Company-operated restaurant revenue
Revenue
Total revenue	$ 106,970	$ 87,707	$ 201,131	$ 180,341
Franchise revenue
Revenue
Total revenue	8,389	6,719	16,001	13,781
Franchise advertising fee revenue
Revenue
Total revenue	$ 6,626	$ 5,178	$ 12,574	$ 10,645