Consolidated Statements Of Comprehensive Income - USD ($)	3 Months Ended		6 Months Ended
	Jun. 28, 2020	Jun. 30, 2019	Jun. 28, 2020	Jun. 30, 2019
Revenues:
Revenue	$ 368,418,000	$ 368,559,000	$ 719,936,000	$ 659,348,000
Costs and expenses:
Cost of sales	104,703,000	109,157,000	207,630,000	191,732,000
Restaurant wages and related expenses	111,888,000	121,140,000	236,463,000	221,332,000
Restaurant rent expense	28,984,000	26,690,000	58,438,000	48,606,000
Other restaurant operating expenses	54,310,000	56,308,000	112,288,000	101,913,000
Advertising expense	14,416,000	14,677,000	28,292,000	26,549,000
General and administrative (including stock-based compensation expense of $1,109, $1,282, $2,241 and $2,808 respectively)	18,581,000	20,620,000	39,368,000	40,344,000
Depreciation and amortization	20,296,000	17,121,000	41,327,000	32,413,000
Impairment and other lease charges	2,941,000	367,000	5,822,000	1,277,000
Other expense (income), net (Note 14)		376,000
Total operating expenses	354,116,000	366,456,000	727,681,000	662,413,000
Income (loss) from operations	14,302,000	2,103,000	(7,745,000)	(3,065,000)
Loss on extinguishment of debt	0	7,443,000	0	7,443,000
Interest expense	6,370,000	6,900,000	13,510,000	12,847,000
Income (loss) before income taxes	7,932,000	(12,240,000)	(21,255,000)	(23,355,000)
Provision (benefit) for income taxes	90,000	(8,508,000)	(6,888,000)	(8,154,000)
Net income (loss)	$ 7,842,000	$ (3,732,000)	$ (14,367,000)	$ (15,201,000)
Basic and diluted net income (loss) per share	$ 0.13	$ (0.09)	$ (0.28)	$ (0.39)
Weighted average common shares outstanding:
Weighted average common shares outstanding (in shares)	50,916,758	41,051,354	50,868,929	38,548,246
Shares used in computing diluted net income (loss) per share (in shares)	60,331,817	41,051,354	50,868,929	38,548,246
Other comprehensive income (loss), net of tax:
Net income (loss)	$ 7,842,000	$ (3,732,000)	$ (14,367,000)	$ (15,201,000)
Change in valuation of interest rate swap (Note 7)	(2,178,000)	0	(7,387,000)	0
Comprehensive income (loss)	5,664,000	(3,732,000)	(21,754,000)	(15,201,000)
Restaurant Sales [Member]
Revenues:
Revenue	368,418,000	365,674,000	719,936,000	656,463,000
Other Revenue [Member]
Revenues:
Revenue	$ 0	$ 2,885,000	$ 0	$ 2,885,000