Condensed Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 20, 2017	Jun. 14, 2016	Jun. 20, 2017	Jun. 14, 2016
Revenue:
Company restaurant sales	$ 104,022	$ 95,917	$ 205,244	$ 189,467
Franchise revenue	3,903	3,576	7,516	6,905
Franchise sublease income	656	533	1,166	1,057
Total revenue	108,581	100,026	213,926	197,429
Restaurant operating expenses:
Food and paper costs	28,770	26,358	56,688	52,487
Labor and related expenses	33,185	30,249	66,406	60,033
Occupancy and other operating expenses	20,918	19,526	41,636	39,649
General and administrative	9,055	8,214	18,360	16,506
Depreciation and amortization	5,278	5,532	10,381	11,018
Occupancy and other - franchise subleases	602	510	1,083	1,013
Pre-opening costs	151	35	177	128
Restaurant closure charges, net	6	(166)	15	12
Loss on disposal of assets, net	340	62	291	137
Total operating expenses	98,305	90,320	195,037	180,983
Income from operations	10,276	9,706	18,889	16,446
Other expense
Interest expense	1,627	1,405	3,170	2,877
Transaction-related costs	0	126	0	191
Total other expense	1,627	1,531	3,170	3,068
Income from operations before provision for income taxes	8,649	8,175	15,719	13,378
Provision for income taxes	3,319	3,311	6,151	5,453
Net income	5,330	4,864	9,568	7,925
Other comprehensive loss:
Change in fair value of interest rate cap, net of tax	(148)	0	(236)	0
Total other comprehensive loss	(148)	0	(236)	0
Comprehensive income	$ 5,182	$ 4,864	$ 9,332	$ 7,925
Earnings per share:
Basic (in dollars per share)	$ 0.14	$ 0.13	$ 0.25	$ 0.21
Diluted (in dollars per share)	$ 0.13	$ 0.13	$ 0.24	$ 0.20
Weighted-average shares outstanding
Basic (in shares)	38,535,855	38,292,215	38,769,895	38,545,115
Diluted (in shares)	39,808,485	38,442,304	40,094,476	38,672,425