Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 18, 2019	Jun. 19, 2018	Jun. 18, 2019	Jun. 19, 2018
Revenue:
Total revenue	$ 121,460	$ 117,813	$ 235,657	$ 230,367
Restaurant operating expenses:
Cost, Direct Material	30,855	30,082	59,673	59,055
Labor and related expenses	36,338	35,422	72,238	70,240
Occupancy and other operating expenses	23,703	22,627	48,136	44,613
General and administrative	10,849	10,321	21,314	20,750
Cooperative Advertising Expense	3,459	3,136	6,590	6,072
Depreciation and amortization	5,813	5,847	11,720	11,761
Occupancy and other - franchise subleases and other	993	651	1,847	1,289
Pre-opening costs	155	199	255	641
Impairment of long-lived assets	3,694	1,661	3,694	1,661
Restaurant closure charges, net	490	(24)	1,130	(37)
Loss on disposal of assets, net	594	87	884	180
Total operating expenses	116,943	110,009	227,481	216,225
Income from operations	4,517	7,804	8,176	14,142
Other expense (income), net
Interest expense	1,722	2,012	3,506	3,922
Other Nonoperating Income	(97)	0	(201)	0
Total other expense, net	1,625	2,012	3,305	3,922
Income from operations before provision for income taxes	2,892	5,792	4,871	10,220
Provision for income taxes	800	1,582	1,354	2,781
Net income	2,092	4,210	3,517	7,439
Other comprehensive (loss) income:
Change in fair value of interest rate cap, net of tax	(131)	115	(270)	289
Reclassification of interest rate cap amortization included in net income	26	10	47	16
Total other comprehensive (loss) income, net	(105)	125	(223)	305
Comprehensive income	$ 1,987	$ 4,335	$ 3,294	$ 7,744
Earnings per share:
Basic (in dollars per share)	$ 0.06	$ 0.11	$ 0.10	$ 0.19
Diluted (in dollars per share)	$ 0.06	$ 0.11	$ 0.09	$ 0.19
Weighted-average shares outstanding
Basic (in shares)	36,821,728	38,299,483	36,988,853	38,370,595
Diluted (in shares)	37,083,799	38,643,873	37,215,059	38,938,106
Product [Member]
Revenue:
Revenue	$ 112,180	$ 109,800	$ 218,083	$ 214,909
Franchise [Member]
Revenue:
Revenue	4,638	4,149	8,703	7,941
Franchise Advertising Contribution [Member]
Revenue:
Revenue	3,459	3,136	6,590	6,072
Franchise Sublease Income [Member]
Revenue:
Revenue	$ 1,183	$ 728	$ 2,281	$ 1,445