Other Gains and Charges - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended				6 Months Ended		9 Months Ended
	Dec. 26, 2018	Sep. 26, 2018	Dec. 27, 2017	Sep. 27, 2017	Dec. 26, 2018	Dec. 27, 2017	Dec. 26, 2018
Other Gains and Charges [Abstract]
Sale Leaseback Transaction, Current Period Gain Recognized	$ 4.6				$ 24.7
Sale leaseback transaction charges	0.2				7.0
Gain (Loss) on Disposition of Assets	0.8		$ 0.3		0.8	$ 0.3
Remodel-related costs	2.6		0.0		3.1	0.0
Restaurant closure charges	2.1		4.3		3.8	4.5
Restaurant impairment charges	1.0		2.0	$ 7.2	1.0	9.2
Foreign currency transaction (gain) loss	0.7		0.9		(0.1)	0.9
Accelerated depreciation	0.5	$ 0.5	0.5		1.0	1.0
Property damages, net of (insurance recoveries)	0.2		0.5		(0.6)	5.1
Cyber security incident charges	0.0		0.0		0.4	0.0	$ 3.2
Lease guarantee charges	$ 0.0		1.4		$ 0.0	$ 1.4
Proceeds from Sale of Equity Method Investments			18.0
Equity Method Investment, Realized (Gain) Loss on Disposal			(0.2)
Reclassification from Accumulated Other Comprehensive Income, Current Period, before Tax			5.4
Reclassifications out of AOCI, current year, net of tax, attributable to prior years			5.9
Other Comprehensive (Income) Loss, Foreign Currency Transaction and Translation Adjustment, before Tax			$ (0.5)