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. 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
Revenue
Company-operated restaurant revenue	$ 107,546	$ 112,067	$ 113,740	$ 108,977	$ 106,261	$ 112,178	$ 111,633	$ 105,756	$ 442,330	$ 435,828	$ 401,701
Cost of operations
Franchise expenses									27,612	24,429	3,335
Total expenses									404,004	445,289	394,877
Loss from operations	5,336	10,118	20,580	2,292	(30,990)	9,492	7,589	4,448	38,326	(9,461)	6,824
Loss before provision for income taxes									34,582	(12,202)	9,116
Net income (loss)	$ 3,498	$ 6,402	$ 14,087	$ 913	$ (23,410)	$ 6,835	$ 5,052	$ 2,529	24,900	(8,994)	8,619
Franchise revenue
Revenue
Company-operated restaurant revenue									28,819	25,771	25,086
Franchise advertising fee revenue
Revenue
Company-operated restaurant revenue									$ 22,399	$ 21,222	$ 0