Reportable Segments (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 29, 2026	Mar. 30, 2025
Segment Reporting [Abstract]
NumberOfReportableSegmentsNotDisclosedFlag	segments
Segment Reporting Information [Line Items]
Total revenues	$ 225.2	$ 214.8
Gross profit	87.3	90.3
Stock based compensation (direct)	4.8	3.7
Gain on disposition of assets	(2.2)	(0.1)
Interest expense, net	21.8	17.7
Closure and impairment charges	0.8	5.8
Amortization of intangible assets	3.8	2.7
Income before income taxes	10.1	12.8
Advertising revenues
Segment Reporting Information [Line Items]
Revenues excluding advertising revenue	71.0	70.5
Operating Segments
Segment Reporting Information [Line Items]
Total revenues	225.2	214.8
Interest expense from finance leases	0.6	0.7
Depreciation and amortization	3.9	3.1
Other segment items	62.3	50.2
Gross profit	87.3	90.3
Stock based compensation (direct)	1.1	1.0
Gain on disposition of assets	(2.2)	(0.1)
Other G&A expenses (direct and allocated)	34.4	32.6
Segment operating profit (loss)	54.0	56.8
Operating Segments | Advertising revenues
Segment Reporting Information [Line Items]
Revenues excluding advertising revenue	71.0	70.5
Operating Segments | Revenues excluding advertising revenue
Segment Reporting Information [Line Items]
Revenues excluding advertising revenue	154.1	144.3
Operating Segments | Franchise
Segment Reporting Information [Line Items]
Total revenues	164.9	166.2
Interest expense from finance leases	0.0	0.0
Depreciation and amortization	0.2	0.1
Other segment items	11.2	10.6
Gross profit	82.6	85.0
Stock based compensation (direct)	1.1	1.0
Gain on disposition of assets	(2.2)	(0.1)
Other G&A expenses (direct and allocated)	31.0	31.2
Segment operating profit (loss)	52.6	52.9
Operating Segments | Franchise | Advertising revenues
Segment Reporting Information [Line Items]
Revenues excluding advertising revenue	71.0	70.5
Operating Segments | Franchise | Revenues excluding advertising revenue
Segment Reporting Information [Line Items]
Revenues excluding advertising revenue	93.9	95.7
Operating Segments | Company-Owned Restaurants Segment
Segment Reporting Information [Line Items]
Total revenues	33.5	21.6
Interest expense from finance leases	0.0	0.0
Depreciation and amortization	1.5	0.6
Other segment items	33.4	21.4
Gross profit	(1.5)	(0.4)
Stock based compensation (direct)	0.0	0.0
Gain on disposition of assets	0.0	0.0
Other G&A expenses (direct and allocated)	3.3	1.4
Segment operating profit (loss)	(4.8)	(1.8)
Operating Segments | Company-Owned Restaurants Segment | Advertising revenues
Segment Reporting Information [Line Items]
Revenues excluding advertising revenue	0.0	0.0
Operating Segments | Company-Owned Restaurants Segment | Revenues excluding advertising revenue
Segment Reporting Information [Line Items]
Revenues excluding advertising revenue	33.5	21.6
Operating Segments | Rental
Segment Reporting Information [Line Items]
Total revenues	26.8	27.0
Interest expense from finance leases	0.6	0.7
Depreciation and amortization	2.2	2.4
Other segment items	17.7	18.2
Gross profit	6.2	5.7
Stock based compensation (direct)	0.0	0.0
Gain on disposition of assets	0.0	0.0
Other G&A expenses (direct and allocated)	0.0	0.0
Segment operating profit (loss)	6.2	5.7
Operating Segments | Rental | Advertising revenues
Segment Reporting Information [Line Items]
Revenues excluding advertising revenue	0.0	0.0
Operating Segments | Rental | Revenues excluding advertising revenue
Segment Reporting Information [Line Items]
Revenues excluding advertising revenue	26.8	27.0
Segment Reporting Excluding Corporate Expenditure
Segment Reporting Information [Line Items]
Depreciation and amortization	4.4	4.5
Stock based compensation (direct)	2.9	2.3
Other G&A expenses (direct and allocated)	10.2	10.9
Interest expense, net	21.8	17.7
Closure and impairment charges	0.8	5.8
Amortization of intangible assets	3.7	2.7
Income before income taxes	$ 10.1	$ 12.8