Condensed Consolidated Statements of Operations - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Oct. 01, 2019	Oct. 02, 2018	Oct. 01, 2019	Oct. 02, 2018
Revenue:
Total revenue	$ 118,304	$ 116,727	$ 348,540	$ 344,648
Restaurant operating costs (exclusive of depreciation and amortization shown separately below):
Other restaurant operating costs	17,161	16,224	50,475	49,997
General and administrative	10,436	10,399	32,424	35,480
Depreciation and amortization	5,458	5,790	16,626	17,407
Pre-opening	266	0	331	50
Restaurant impairments, closure costs and asset disposals	336	1,792	3,640	5,952
Total costs and expenses	113,260	114,595	343,348	349,356
Income (loss) from operations	5,044	2,132	5,192	(4,708)
Loss on extinguishment of debt	0	0	0	626
Interest expense, net	737	1,093	2,298	3,385
Income (loss) before income taxes	4,307	1,039	2,894	(8,719)
Provision (benefit) for income taxes	64	(11)	64	(259)
Net income (loss) and comprehensive income (loss)	4,243	1,050	2,830	(8,460)
Net income (loss) attributable to common stockholders	$ 4,243	$ 1,050	$ 2,830	$ (8,460)
Earnings (loss) per share of Class A and Class B common stock, combined:
Basic (USD per share)	$ 0.10	$ 0.02	$ 0.06	$ (0.20)
Diluted (USD per share)	$ 0.09	$ 0.02	$ 0.06	$ (0.20)
Weighted average shares of Class A and Class B common stock outstanding, combined:
Basic (in shares)	43,990,049	43,094,524	44,007,345	41,798,640
Diluted (in shares)	44,899,176	44,829,363	45,078,539	41,798,640
Restaurant revenue
Revenue:
Total revenue	$ 116,759	$ 115,552	$ 344,382	$ 341,616
Restaurant operating costs (exclusive of depreciation and amortization shown separately below):
Cost of goods and services sold	29,544	30,617	89,083	90,962
Labor
Restaurant operating costs (exclusive of depreciation and amortization shown separately below):
Cost of goods and services sold	37,951	37,738	113,920	112,353
Franchising royalties and fees, and other
Revenue:
Total revenue	1,545	1,175	4,158	3,032
Occupancy
Restaurant operating costs (exclusive of depreciation and amortization shown separately below):
Cost of goods and services sold	$ 12,108	$ 12,035	$ 36,849	$ 37,155