Shareholders Deficit - Changes in Shareholders' Deficit (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	Jun. 28, 2018
Increase (Decrease) in Stockholders' Deficit [Roll Forward]
Beginning balance	$ (815.9)	$ (718.3)	$ (539.0)	$ (493.6)	$ (718.3)	$ (493.6)
Effect of ASC 606 adoption		(7.4)
Realized foreign currency translation			5.4
Net income	32.0	26.4	25.3	9.9	58.4	35.2
Other comprehensive income	(0.6)	0.3	(0.2)	1.5	(0.3)	0.8
Dividends	(14.5)	(15.5)	(17.9)	(18.8)
Stock-based compensation	3.6	3.6	2.8	3.5
Purchases of treasury stock	(62.1)	(105.5)	(30.1)	(41.7)
Issuances of common stock	2.3	0.5	0.8	0.2
Ending balance	(855.2)	(815.9)	(552.9)	(539.0)	(855.2)	(552.9)
Common Stock [Member]
Increase (Decrease) in Stockholders' Deficit [Roll Forward]
Beginning balance	17.6	17.6	17.6	17.6	17.6	17.6
Effect of ASC 606 adoption		0.0
Realized foreign currency translation			0.0
Net income	0.0	0.0	0.0	0.0
Other comprehensive income	0.0	0.0	0.0	0.0
Dividends	0.0	0.0	0.0	0.0
Stock-based compensation	0.0	0.0	0.0	0.0
Purchases of treasury stock	0.0	0.0	0.0	0.0
Issuances of common stock	0.0	0.0	0.0	0.0
Ending balance	17.6	17.6	17.6	17.6	17.6	17.6
Additional Paid-in Capital [Member]
Increase (Decrease) in Stockholders' Deficit [Roll Forward]
Beginning balance	503.9	511.6	503.1	502.1	511.6	502.1
Effect of ASC 606 adoption		0.0
Realized foreign currency translation			0.0
Net income	0.0	0.0	0.0	0.0
Other comprehensive income	0.0	0.0	0.0	0.0
Dividends	0.0	0.0	0.0	0.0
Stock-based compensation	3.6	3.6	2.8	3.5
Purchases of treasury stock	6.9	(7.5)	0.0	(0.1)
Issuances of common stock	(0.2)	(3.8)	(0.8)	(2.4)
Ending balance	514.2	503.9	505.1	503.1	514.2	505.1
Retained Earnings [Member]
Increase (Decrease) in Stockholders' Deficit [Roll Forward]
Beginning balance	2,686.5	2,683.0	2,618.2	2,627.1	2,683.0	2,627.1
Effect of ASC 606 adoption		(7.4)					$ (7.4)
Realized foreign currency translation			0.0
Net income	32.0	26.4	25.3	9.9
Other comprehensive income	0.0	0.0	0.0	0.0
Dividends	(14.5)	(15.5)	(17.9)	(18.8)
Stock-based compensation	0.0	0.0	0.0	0.0
Purchases of treasury stock	0.0	0.0	0.0	0.0
Issuances of common stock	0.0	0.0	0.0	0.0
Ending balance	2,704.0	2,686.5	2,625.6	2,618.2	2,704.0	2,625.6
Treasury Stock [Member]
Increase (Decrease) in Stockholders' Deficit [Roll Forward]
Beginning balance	(4,018.4)	(3,924.7)	(3,667.5)	(3,628.5)	(3,924.7)	(3,628.5)
Effect of ASC 606 adoption		0.0
Realized foreign currency translation			0.0
Net income	0.0	0.0	0.0	0.0
Other comprehensive income	0.0	0.0	0.0	0.0
Dividends	0.0	0.0	0.0	0.0
Stock-based compensation	0.0	0.0	0.0	0.0
Purchases of treasury stock	(69.0)	(98.0)	(30.1)	(41.6)
Issuances of common stock	2.5	4.3	1.6	2.6
Ending balance	(4,084.9)	(4,018.4)	(3,696.0)	(3,667.5)	(4,084.9)	(3,696.0)
Accumulated Other Comprehensive Income (Loss) [Member]
Increase (Decrease) in Stockholders' Deficit [Roll Forward]
Beginning balance	(5.5)	(5.8)	(10.4)	(11.9)	(5.8)	(11.9)
Effect of ASC 606 adoption		0.0
Realized foreign currency translation			5.4
Net income	0.0	0.0	0.0	0.0
Other comprehensive income	(0.6)	0.3	(0.2)	1.5
Dividends	0.0	0.0	0.0	0.0
Stock-based compensation	0.0	0.0	0.0	0.0
Purchases of treasury stock	0.0	0.0	0.0	0.0
Issuances of common stock	0.0	0.0	0.0	0.0
Ending balance	$ (6.1)	$ (5.5)	$ (5.2)	$ (10.4)	$ (6.1)	$ (5.2)

Amount of increase to additional paid-in capital (APIC) from recognition of equity-based compensation.

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Gross value of stock (or other type of equity) issued during the period as a result of any equity-based compensation plan other than an employee stock ownership plan (ESOP). Stock issued could result from the issuance of restricted stock, the exercise of stock options, stock issued under employee stock purchase plans, and/or other employee benefit plans.

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