SHAREHOLDERS' DEFICIT (Changes in Shareholders' Deficit) (Details) - USD ($) $ in Millions	3 Months Ended				6 Months Ended
	Dec. 23, 2020	Sep. 23, 2020	Dec. 25, 2019	Sep. 25, 2019	Dec. 23, 2020	Dec. 25, 2019
Increase (Decrease) in Stockholders' Deficit [Roll Forward]
Beginning balance	$ (465.1)	$ (479.1)	$ (585.1)	$ (778.2)	$ (479.1)	$ (778.2)
Net income	12.0	10.7	27.9	14.9	22.7	42.8
Other comprehensive income (loss)	0.5	0.3	0.1	(0.2)	0.8	(0.1)
Dividends	0.0	0.0	(14.6)	(14.6)
Stock-based compensation	3.0	3.9	2.6	7.1
Purchases of treasury stock	0.0	(3.9)	0.0	(11.3)
Issuances of common stock	5.5	3.0	0.2	1.3
Retirement of treasury stock			0.0
Ending balance	(444.1)	(465.1)	(568.9)	(585.1)	(444.1)	(568.9)
Cumulative Effect, Period of Adoption, Adjustment | ASC 842 Leases [Member]
Increase (Decrease) in Stockholders' Deficit [Roll Forward]
Beginning balance				195.9		195.9
Common Stock [Member]
Increase (Decrease) in Stockholders' Deficit [Roll Forward]
Beginning balance	7.0	7.0	17.6	17.6	7.0	17.6
Net income	0.0	0.0	0.0	0.0
Other comprehensive income (loss)	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
Retirement of treasury stock			(11.4)
Ending balance	7.0	7.0	6.2	17.6	7.0	6.2
Additional Paid-in Capital [Member]
Increase (Decrease) in Stockholders' Deficit [Roll Forward]
Beginning balance	663.2	669.4	525.1	522.0	669.4	522.0
Net income	0.0	0.0	0.0	0.0
Other comprehensive income (loss)	0.0	0.0	0.0	0.0
Dividends	0.0	0.0	0.0	0.0
Stock-based compensation	3.0	3.9	2.6	7.1
Purchases of treasury stock	0.0	(1.1)	0.0	(0.3)
Issuances of common stock	1.2	(9.0)	(0.4)	(3.7)
Retirement of treasury stock			0.0
Ending balance	667.4	663.2	527.3	525.1	667.4	527.3
(Accumulated Deficit) Retained Earnings [Member]
Increase (Decrease) in Stockholders' Deficit [Roll Forward]
Beginning balance	(386.8)	(397.5)	2,967.4	2,771.2	(397.5)	2,771.2
Net income	12.0	10.7	27.9	14.9
Other comprehensive income (loss)	0.0	0.0	0.0	0.0
Dividends	0.0	0.0	(14.6)	(14.6)
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
Retirement of treasury stock			(3,345.4)
Ending balance	(374.8)	(386.8)	(364.7)	2,967.4	(374.8)	(364.7)
(Accumulated Deficit) Retained Earnings [Member] | Cumulative Effect, Period of Adoption, Adjustment | ASC 842 Leases [Member]
Increase (Decrease) in Stockholders' Deficit [Roll Forward]
Beginning balance				195.9		195.9
Treasury Stock [Member]
Increase (Decrease) in Stockholders' Deficit [Roll Forward]
Beginning balance	(742.6)	(751.8)	(4,089.4)	(4,083.4)	(751.8)	(4,083.4)
Net income	0.0	0.0	0.0	0.0
Other comprehensive income (loss)	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	(2.8)	0.0	(11.0)
Issuances of common stock	4.3	12.0	0.6	5.0
Retirement of treasury stock			3,356.8
Ending balance	(738.3)	(742.6)	(732.0)	(4,089.4)	(738.3)	(732.0)
Accumulated Other Comprehensive (Loss) Income [Member]
Increase (Decrease) in Stockholders' Deficit [Roll Forward]
Beginning balance	(5.9)	(6.2)	(5.8)	(5.6)	(6.2)	(5.6)
Net income	0.0	0.0	0.0	0.0
Other comprehensive income (loss)	0.5	0.3	0.1	(0.2)
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
Retirement of treasury stock			0.0
Ending balance	$ (5.4)	$ (5.9)	$ (5.7)	$ (5.8)	$ (5.4)	$ (5.7)