Condensed Consolidated Statements of Operations - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jul. 02, 2019	Jun. 30, 2020	Jul. 02, 2019
Revenue:
Total revenue	$ 80,157	$ 120,190	$ 180,505	$ 230,236
Restaurant operating costs (exclusive of depreciation and amortization shown):
Other restaurant operating costs	15,789	16,858	32,478	33,314
General and administrative	10,034	11,848	20,588	21,988
Depreciation and amortization	5,397	5,661	10,732	11,168
Pre-opening	71	65	144	65
Restaurant impairments, closure costs and asset disposals	2,558	2,884	3,614	3,304
Total costs and expenses	92,682	118,952	197,884	230,088
(Loss) income from operations	(12,525)	1,238	(17,379)	148
Interest expense, net	920	800	1,888	1,561
(Loss) income before taxes	(13,445)	438	(19,267)	(1,413)
Provision for income taxes	33	0	46	0
Net (loss) income and comprehensive (loss) income	$ (13,478)	$ 438	$ (19,313)	$ (1,413)
(Loss) earnings per Class A and Class B common stock, combined
Basic (USD per share)	$ (0.30)	$ 0.01	$ (0.44)	$ (0.03)
Diluted (USD per share)	$ (0.30)	$ 0.01	$ (0.44)	$ (0.03)
Weighted average shares of Class A and Class B common stock outstanding, combined:
Basic (in shares)	44,212,751	43,964,175	44,177,648	43,955,580
Diluted (in shares)	44,212,751	45,075,888	44,177,648	43,955,580
Restaurant revenue
Revenue:
Total revenue	$ 80,021	$ 118,858	$ 178,737	$ 227,623
Restaurant operating costs (exclusive of depreciation and amortization shown):
Restaurant operating costs	20,020	30,448	45,224	59,539
Franchising royalties and fees, and other
Revenue:
Total revenue	136	1,332	1,768	2,613
Labor
Restaurant operating costs (exclusive of depreciation and amortization shown):
Restaurant operating costs	27,137	38,877	61,368	75,969
Occupancy
Restaurant operating costs (exclusive of depreciation and amortization shown):
Restaurant operating costs	$ 11,676	$ 12,311	$ 23,736	$ 24,741