Condensed Consolidated Statements of Operations - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jul. 03, 2018	Jul. 04, 2017	Jul. 03, 2018	Jul. 04, 2017
Revenue:
Restaurant revenue	$ 116,451	$ 111,628	$ 226,064	$ 227,155
Franchising royalties and fees	944	1,164	1,857	2,352
Total revenue	117,395	112,792	227,921	229,507
Restaurant operating costs (exclusive of depreciation and amortization shown separately below):
Cost of sales	31,089	29,598	60,345	61,685
Labor	38,043	36,430	74,615	76,024
Occupancy	12,357	12,630	25,120	26,631
Other restaurant operating costs	16,875	16,194	33,773	33,341
General and administrative	14,813	9,393	25,081	20,059
Depreciation and amortization	5,797	6,279	11,617	12,546
Pre-opening	3	246	50	791
Restaurant impairments, closure costs and asset disposals	2,580	2,830	4,160	24,884
Total costs and expenses	121,557	113,600	234,761	255,961
Loss from operations	(4,162)	(808)	(6,840)	(26,454)
Loss on extinguishment of debt	626	0	626	0
Interest expense, net	1,154	927	2,292	1,935
Loss before income taxes	(5,942)	(1,735)	(9,758)	(28,389)
(Benefit) provision for income taxes	(7)	80	(248)	271
Net loss	(5,935)	(1,815)	(9,510)	(28,660)
Accretion of preferred stock to redemption value	0	(7,001)	0	(7,967)
Net loss attributable to common stockholders	$ (5,935)	$ (8,816)	$ (9,510)	$ (36,627)
Loss per share of Class A and Class B common stock, combined:
Basic (USD per share)	$ (0.14)	$ (0.22)	$ (0.23)	$ (1.06)
Diluted (USD per share)	$ (0.14)	$ (0.22)	$ (0.23)	$ (1.06)
Weighted average shares of Class A and Class B common stock outstanding, combined:
Basic (in shares)	41,172,924	40,779,277	41,150,698	34,404,222
Diluted (in shares)	41,172,924	40,779,277	41,150,698	34,404,222