Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended
	Mar. 26, 2019	Mar. 27, 2018
Revenue:
Total revenue	$ 114,197	$ 112,554
Restaurant operating expenses:
Cost, Direct Material	28,818	28,973
Labor and related expenses	35,900	34,818
Occupancy and other operating expenses	24,433	21,986
General and administrative	10,465	10,429
Cooperative Advertising Expense	3,131	2,936
Depreciation and amortization	5,907	5,914
Occupancy and other - franchise subleases and other	854	638
Pre-opening costs	100	442
Impairment of long-lived assets	0	0
Restaurant closure charges, net	640	(13)
Loss on disposal of assets, net	290	93
Total operating expenses	110,538	106,216
Income from operations	3,659	6,338
Other expense (income), net
Interest expense	1,784	1,910
Other Nonoperating Income	(104)	0
Total other expense, net	1,680	1,910
Income from operations before provision for income taxes	1,979	4,428
Provision for income taxes	554	1,199
Net income	1,425	3,229
Other comprehensive (loss) income:
Change in fair value of interest rate cap, net of tax	(139)	174
Reclassification of interest rate cap amortization included in net income	21	6
Total other comprehensive (loss) income, net	(118)	180
Comprehensive income	$ 1,307	$ 3,409
Earnings per share:
Basic (in dollars per share)	$ 0.04	$ 0.08
Diluted (in dollars per share)	$ 0.04	$ 0.08
Weighted-average shares outstanding
Basic (in shares)	37,155,978	38,441,707
Diluted (in shares)	37,346,319	39,224,070
Product [Member]
Revenue:
Revenue	$ 105,903	$ 105,109
Franchise [Member]
Revenue:
Revenue	4,065	3,792
Franchise Advertising Contribution [Member]
Revenue:
Revenue	3,131	2,936
Franchise Sublease Income [Member]
Revenue:
Revenue	$ 1,098	$ 717