Segment Information (Details) $ in Thousands	3 Months Ended
	Mar. 27, 2024 USD ($) segment	Mar. 29, 2023 USD ($)	Dec. 27, 2023 USD ($)
Segment Reporting [Abstract]
Number of operating segments | segment	2
Segment Reporting Information [Line Items]
Total operating revenue	$ 109,974	$ 117,471
General and administrative expenses	21,222	20,118
Depreciation and amortization	3,581	3,656
Operating (gains), losses and other charges, net	(327)	(1,329)
Total other operating expenses	24,476	22,445
Operating income	10,006	16,147
Interest expense, net	4,420	4,505
Other nonoperating expense (income), net	(637)	10,093
Income before income taxes	6,223	1,549
Provision for income taxes	1,532	952
Net income	4,691	597
Total assets	460,411		$ 464,818
Operating Segments
Segment Reporting Information [Line Items]
Total operating revenue	109,974	117,471
Total restaurant-level operating margin	34,482	38,592
Total assets	460,411		464,818
Operating Segments | Denny’s
Segment Reporting Information [Line Items]
Total operating revenue	104,011	112,230
Total restaurant-level operating margin	33,660	36,640
Total assets	336,143		340,136
Operating Segments | Other
Segment Reporting Information [Line Items]
Total operating revenue	5,963	5,241
Total restaurant-level operating margin	822	$ 1,952
Total assets	$ 124,268		$ 124,682