Segment Information (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 25, 2024 USD ($)	Sep. 27, 2023 USD ($)	Sep. 25, 2024 USD ($) segment	Sep. 27, 2023 USD ($)	Dec. 27, 2023 USD ($)
Segment Reporting [Abstract]
Number of operating segments | segment			2
Segment Reporting Information [Line Items]
Total operating revenue	$ 111,759	$ 114,183	$ 337,660	$ 348,569
General and administrative expenses	19,831	18,237	61,539	58,515
Depreciation and amortization	3,622	3,605	10,938	10,878
Goodwill impairment charges	0	0	20	0
Operating (gains), losses and other charges, net	746	2,620	1,984	2,467
Total other operating expenses	24,199	24,462	74,481	71,860
Operating income	11,741	14,018	30,862	45,099
Interest expense, net	4,571	4,381	13,564	13,288
Other nonoperating (income) expense, net	(824)	43	(1,685)	9,470
Income before income taxes	7,994	9,594	18,983	22,341
Provision for income taxes	1,478	1,686	4,208	5,298
Net income	6,516	7,908	14,775	17,043
Total assets	461,623		461,623		$ 464,818
Operating Segments
Segment Reporting Information [Line Items]
Total operating revenue	111,759	114,183	337,660	348,569
Total restaurant-level operating margin	35,940	38,480	105,343	116,959
Total assets	461,623		461,623		464,818
Operating Segments | Denny’s
Segment Reporting Information [Line Items]
Total operating revenue	105,365	109,136	318,728	332,952
Total restaurant-level operating margin	35,015	36,944	102,750	111,525
Total assets	320,642		320,642		340,136
Operating Segments | Other
Segment Reporting Information [Line Items]
Total operating revenue	6,394	5,047	18,932	15,617
Total restaurant-level operating margin	925	$ 1,536	2,593	$ 5,434
Total assets	$ 140,981		$ 140,981		$ 124,682