Condensed Consolidated Statements of Operations - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 29, 2021	Jun. 30, 2020	Jun. 29, 2021	Jun. 30, 2020
Revenue:
Total revenue	$ 125,649	$ 80,157	$ 235,226	$ 180,505
Restaurant operating costs (exclusive of depreciation and amortization shown separately below):
Other restaurant operating costs	21,082	15,789	41,287	32,478
General and administrative	12,978	10,034	23,907	20,588
Depreciation and amortization	5,576	5,397	11,163	10,732
Pre-opening	163	71	221	144
Restaurant impairments, closure costs and asset disposals	390	2,558	1,621	3,614
Total costs and expenses	119,439	92,682	230,381	197,884
Income (loss) from operations	6,210	(12,525)	4,845	(17,379)
Interest expense, net	498	920	1,120	1,888
Income (loss) before taxes	5,712	(13,445)	3,725	(19,267)
Provision for income taxes	29	33	19	46
Net income (loss)	$ 5,683	$ (13,478)	$ 3,706	$ (19,313)
Earnings (loss) per Class A and Class B common stock, combined
Basic (USD per share)	$ 0.12	$ (0.30)	$ 0.08	$ (0.44)
Diluted (USD per share)	$ 0.12	$ (0.30)	$ 0.08	$ (0.44)
Weighted average shares of Class A and Class B common stock outstanding, combined:
Basic (in shares)	45,506,476	44,212,751	45,303,160	44,177,648
Diluted (in shares)	46,246,169	44,212,751	45,992,119	44,177,648
Restaurant revenue
Revenue:
Total revenue	$ 123,715	$ 80,021	$ 231,459	$ 178,737
Restaurant operating costs (exclusive of depreciation and amortization shown separately below):
Restaurant operating costs	30,805	20,020	57,782	45,224
Franchising royalties and fees, and other
Revenue:
Total revenue	1,934	136	3,767	1,768
Labor
Restaurant operating costs (exclusive of depreciation and amortization shown separately below):
Restaurant operating costs	36,926	27,137	71,232	61,368
Occupancy
Restaurant operating costs (exclusive of depreciation and amortization shown separately below):
Restaurant operating costs	$ 11,519	$ 11,676	$ 23,168	$ 23,736