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Summary of Significant Accounting Policies - Summary of Impact on Statement of Operations from Adoption of New Accounting Pronouncements (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 26, 2018	Sep. 26, 2018	Jun. 27, 2018	Mar. 28, 2018	Dec. 27, 2017	Sep. 27, 2017	Jun. 28, 2017	Mar. 29, 2017	Dec. 26, 2018	Dec. 27, 2017	Dec. 28, 2016
Revenue
Company-operated restaurant revenue	$ 106,261	$ 112,178	$ 111,633	$ 105,756	$ 95,202	$ 101,155	$ 105,573	$ 99,771	$ 435,828	$ 401,701	$ 380,123
Cost of operations
Franchise expenses									24,429	3,335	3,823
Total expenses									445,289	394,877	345,522
Loss from operations	(30,990)	9,492	7,589	4,448	(9,665)	(5,612)	12,740	9,361	(9,461)	6,824	34,629
Loss before provision for income taxes									(12,202)	9,116	31,122
Net (loss) income	$ (23,410)	$ 6,835	$ 5,052	$ 2,529	$ (38)	$ (4,039)	$ 7,819	$ 4,877	(8,994)	8,619	18,339
Franchise revenue
Revenue
Company-operated restaurant revenue									25,771	25,086	24,655
Franchise advertising fee revenue
Revenue
Company-operated restaurant revenue									21,222	$ 0	$ 0
Adjustments \| Accounting Standards Update 2014-09
Revenue
Company-operated restaurant revenue									21,388
Cost of operations
Franchise expenses									21,222
Total expenses									21,222
Loss from operations									166
Loss before provision for income taxes									166
Net (loss) income									166
Adjustments \| Franchise revenue \| Accounting Standards Update 2014-09
Revenue
Company-operated restaurant revenue									166
Adjustments \| Franchise advertising fee revenue \| Accounting Standards Update 2014-09
Revenue
Company-operated restaurant revenue									21,222
Balances without adoption of Topic 606
Revenue
Company-operated restaurant revenue									414,440
Cost of operations
Franchise expenses									3,207
Total expenses									424,067
Loss from operations									(9,627)
Loss before provision for income taxes									(12,368)
Net (loss) income									(9,160)
Balances without adoption of Topic 606 \| Franchise revenue
Revenue
Company-operated restaurant revenue									25,605
Balances without adoption of Topic 606 \| Franchise advertising fee revenue
Revenue
Company-operated restaurant revenue									$ 0