Revenue Recognition - Pro Forma Adjustments to Cash flows from Operating Activities (Details) - USD ($) $ in Millions	3 Months Ended				6 Months Ended
	Dec. 26, 2018	Sep. 26, 2018	Dec. 27, 2017	Sep. 27, 2017	Dec. 26, 2018	Dec. 27, 2017
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Net income	$ 32.0	$ 26.4	$ 25.3	$ 9.9	$ 58.4	$ 35.2
Depreciation and amortization	36.1		$ 37.7		73.1	76.2
Stock-based compensation					7.2	6.3
Restructure charges and other impairments					8.4	14.5
Net (gain) loss on disposal of assets					(18.3)	1.3
Other					1.3	1.7
Accounts receivable, net					(32.3)	(37.2)
Inventories					(0.1)	0.5
Restaurant supplies					(0.2)	(1.1)
Prepaid expenses					(2.4)	2.0
Deferred income taxes, net					(77.8)	10.5
Other assets					(0.2)	(0.2)
Accounts payable					4.7	(4.3)
Gift card liability					42.1	40.3
Accrued payroll					(8.0)	(7.4)
Other accrued liabilities					(2.6)	5.0
Current income taxes					3.4	(20.4)
Other liabilities					(0.7)	(2.5)
Net cash provided by operating activities					56.2	$ 119.7
Difference between Revenue Guidance in Effect before and after Topic 606 [Member] | Accounting Standards Update 2014-09 [Member]
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Net income	(0.5)				(0.3)
Depreciation and amortization	0.0				0.0
Stock-based compensation					0.0
Restructure charges and other impairments					0.0
Net (gain) loss on disposal of assets					0.0
Other					0.0
Accounts receivable, net					0.0
Inventories					0.0
Restaurant supplies					0.0
Prepaid expenses					0.0
Deferred income taxes, net					0.0
Other assets					0.0
Accounts payable					0.0
Gift card liability					(0.3)
Accrued payroll					0.0
Other accrued liabilities					0.6
Current income taxes					0.0
Other liabilities					0.0
Net cash provided by operating activities					0.0
Calculated under Revenue Guidance in Effect before Topic 606 [Member] | Accounting Standards Update 2014-09 [Member]
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Net income	31.5				58.1
Depreciation and amortization	$ 36.1				73.1
Stock-based compensation					7.2
Restructure charges and other impairments					8.4
Net (gain) loss on disposal of assets					(18.3)
Other					1.3
Accounts receivable, net					(32.3)
Inventories					(0.1)
Restaurant supplies					(0.2)
Prepaid expenses					(2.4)
Deferred income taxes, net					(77.8)
Other assets					(0.2)
Accounts payable					4.7
Gift card liability					41.8
Accrued payroll					(8.0)
Other accrued liabilities					(2.0)
Current income taxes					3.4
Other liabilities					(0.7)
Net cash provided by operating activities					$ 56.2