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Quarterly Data (Unaudited) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 25, 2019	Sep. 25, 2019	Jun. 26, 2019	Mar. 27, 2019	Dec. 26, 2018	Sep. 26, 2018	Jun. 27, 2018	Mar. 28, 2018	Dec. 25, 2019	Dec. 26, 2018	Dec. 27, 2017
Disaggregation of Revenue [Line Items]
Revenue	$ 113,836	$ 124,258	$ 151,884	$ 151,411	$ 159,549	$ 158,023	$ 157,334	$ 155,273	$ 541,389	$ 630,179	$ 529,169
Total operating costs and expenses	87,273	56,084	105,769	127,280	139,789	139,554	138,374	138,848	376,406	556,565	458,471
Operating income	26,563	68,174	46,115	24,131	19,760	18,469	18,960	16,425	164,983	73,614	70,698
Net income	$ 18,559	$ 49,122	$ 34,239	$ 15,490	$ 11,503	$ 10,805	$ 11,626	$ 9,759	$ 117,410	$ 43,693	$ 39,594
Basic net income per share (in dollars per share)	$ 0.32	$ 0.83	$ 0.57	$ 0.25	$ 0.19	$ 0.17	$ 0.18	$ 0.15	$ 1.96	$ 0.69	$ 0.58
Diluted net income per share (in dollars per share)	$ 0.31	$ 0.80	$ 0.55	$ 0.24	$ 0.18	$ 0.16	$ 0.18	$ 0.15	$ 1.90	$ 0.67	$ 0.56
Total gains (losses) on sales of company restaurants									$ 93,608	$ 513	$ 1,729
Real Estate
Disaggregation of Revenue [Line Items]
Total gains (losses) on sales of company restaurants									$ 11,874	$ 0	1,918
Franchised Risk Type | Revenue Benchmark
Disaggregation of Revenue [Line Items]
Franchise revenue, percentage									96.00%	90.00%
Company restaurant sales
Disaggregation of Revenue [Line Items]
Total gains (losses) on sales of company restaurants									$ 82,866	$ (746)	(268)
Company restaurant sales
Disaggregation of Revenue [Line Items]
Revenue	$ 48,803	$ 63,582	$ 95,447	$ 98,545	$ 104,389	$ 103,609	$ 102,741	$ 101,193	306,377	411,932	390,352
Franchise and license revenue
Disaggregation of Revenue [Line Items]
Revenue	$ 65,033	$ 60,676	$ 56,437	$ 52,866	$ 55,160	$ 54,414	$ 54,593	$ 54,080	$ 235,012	$ 218,247	$ 138,817

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