Condensed Consolidated Statements of Operations - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 27, 2016	Sep. 29, 2015	Sep. 27, 2016	Sep. 29, 2015
Revenue:
Restaurant revenue	$ 121,442	$ 116,151	$ 354,511	$ 334,767
Franchising royalties and fees	1,239	1,177	3,563	3,555
Total revenue	122,681	117,328	358,074	338,322
Restaurant operating costs (exclusive of depreciation and amortization shown separately below):
Cost of sales	33,112	30,941	95,465	88,616
Labor	40,973	37,687	117,723	105,865
Occupancy	13,792	12,911	40,794	37,609
Other restaurant operating costs	18,470	17,003	53,958	46,878
General and administrative	15,251	9,384	35,128	27,034
Depreciation and amortization	7,006	7,117	20,983	20,959
Pre-opening	856	1,108	2,689	3,150
Restaurant impairments, closure costs and asset disposals	2,283	16,479	14,547	22,815
Total costs and expenses	131,743	132,630	381,287	352,926
Loss from operations	(9,062)	(15,302)	(23,213)	(14,604)
Interest expense, net	738	391	1,964	818
Loss before income taxes	(9,800)	(15,693)	(25,177)	(15,422)
Provision (benefit) for income taxes	41	(5,872)	1,124	(5,911)
Net loss	$ (9,841)	$ (9,821)	$ (26,301)	$ (9,511)
Loss per share of Class A and Class B common stock, combined:
Basic (USD per share)	$ (0.35)	$ (0.35)	$ (0.95)	$ (0.32)
Diluted (USD per share)	$ (0.35)	$ (0.35)	$ (0.95)	$ (0.32)
Weighted average shares of Class A and Class B common stock outstanding, combined:
Basic (in shares)	27,802,020	28,253,859	27,786,827	29,349,061
Diluted (in shares)	27,802,020	28,253,859	27,786,827	29,349,061