Segment Reporting (Reconciliation Of Net Income To Restaurant-Level EBITDA) (Details) - USD ($) $ in Thousands	3 Months Ended						4 Months Ended		12 Months Ended
	Sep. 06, 2016	Jun. 14, 2016	Mar. 22, 2016	Sep. 08, 2015	Jun. 16, 2015	Mar. 24, 2015	Dec. 27, 2016	Dec. 29, 2015	Dec. 27, 2016	Dec. 29, 2015	Dec. 30, 2014
Segment Reporting [Abstract]
Net income	$ 786	$ 4,444	$ 5,411	$ (1,035)	$ 3,713	$ 5,394	$ 7,125	$ 7,926	$ 17,766	$ 15,998	$ 16,597
Income tax expense									6,808	5,507	7,723
Income before income taxes									24,574	21,505	24,320
Interest expense, net of capitalized interest									70	77	113
Other									432	236	107
Operating income	$ 1,118	$ 6,325	$ 7,879	(2,080)	$ 5,494	$ 7,800	9,754	10,604	25,076	21,818	24,540
Pre-opening costs									3,446	5,228	4,735
General and administrative costs									25,924	23,111	20,537
Lease termination and closing costs							900	$ 1,400	1,031	1,386
Secondary public offering costs											5
Impairment charges				$ 3,200			$ 600		598	3,248	3,536
Depreciation and amortization									18,865	16,776	13,598
Restaurant-level EBITDA									$ 74,940	$ 71,567	$ 66,951