UNAUDITED CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY - USD ($) shares in Thousands, $ in Millions	Total	ATM Program	Total Shareholders' Equity	Total Shareholders' Equity ATM Program	Common Stock	Common Stock ATM Program	Additional Paid-in Capital	Additional Paid-in Capital ATM Program	Accumulated Deficit	Accumulated Other Comprehensive Income	Non-controlling Interest from Discontinued Operations
Balance at beginning of period (shares) at Jun. 28, 2020					109,230
Balance at beginning of period at Jun. 28, 2020	$ 2,089.2		$ 2,083.1		$ 0.1		$ 3,106.2		$ (1,039.2)	$ 16.0	$ 6.1
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	(184.1)		(184.4)						(184.4)		0.3
Unrealized loss on available-for-sale securities	0.0		0.0							0.0
Comprehensive loss	(184.1)		(184.4)								0.3
Tax withholding on vested equity awards	(22.7)		(22.7)				(22.7)
Stock-based compensation	16.2		16.2				16.2
Exercise of stock options and issuance of shares (shares)					1,066
Exercise of stock options and issuance of shares	16.5		16.5				16.5
Balance at end of period (shares) at Sep. 27, 2020					110,296
Balance at end of period at Sep. 27, 2020	1,915.1		1,908.7		$ 0.1		3,116.2		(1,223.6)	16.0	6.4
Balance at beginning of period (shares) at Jun. 28, 2020					109,230
Balance at beginning of period at Jun. 28, 2020	2,089.2		2,083.1		$ 0.1		3,106.2		(1,039.2)	16.0	6.1
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	(374.9)
Unrealized loss on available-for-sale securities	(3.0)
Comprehensive loss	(387.4)
Balance at end of period (shares) at Mar. 28, 2021					115,425
Balance at end of period at Mar. 28, 2021	2,247.0		2,247.0		$ 0.1		3,658.9		(1,415.5)	3.5	0.0
Balance at beginning of period (shares) at Sep. 27, 2020					110,296
Balance at beginning of period at Sep. 27, 2020	1,915.1		1,908.7		$ 0.1		3,116.2		(1,223.6)	16.0	6.4
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	(82.7)		(83.0)						(83.0)		0.3
Unrealized loss on available-for-sale securities	(0.5)		(0.5)							(0.5)
Comprehensive loss	(83.2)		(83.5)								0.3
Tax withholding on vested equity awards	(1.6)		(1.6)				(1.6)
Stock-based compensation	18.6		18.6				18.6
Exercise of stock options and issuance of shares (shares)					681
Exercise of stock options and issuance of shares	22.7		22.7				22.7
Balance at end of period (shares) at Dec. 27, 2020					110,977
Balance at end of period at Dec. 27, 2020	1,871.6		1,864.9		$ 0.1		3,155.9		(1,306.6)	15.5	6.7
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	(108.1)		(108.9)						(108.9)		0.8
Reclassification of currency translation gain to loss on sale of discontinued operations	(9.5)		(9.5)							(9.5)
Unrealized loss on available-for-sale securities	(2.5)		(2.5)							(2.5)
Comprehensive loss	(120.1)		(120.9)								0.8
Tax withholding on vested equity awards	(7.4)		(7.4)				(7.4)
Stock-based compensation	19.5		19.5				19.5
Exercise of stock options and issuance of shares (shares)					225	4,223
Exercise of stock options and issuance of shares	1.8	$ 489.1	1.8	$ 489.1			1.8	$ 489.1
Reclassification of noncontrolling interest to loss on sale of discontinued operations	(7.5)										(7.5)
Balance at end of period (shares) at Mar. 28, 2021					115,425
Balance at end of period at Mar. 28, 2021	$ 2,247.0		$ 2,247.0		$ 0.1		3,658.9		(1,415.5)	3.5	$ 0.0
Balance at beginning of period (shares) at Jun. 27, 2021	115,691				115,691
Balance at beginning of period at Jun. 27, 2021	$ 2,116.5				$ 0.1		3,676.8		(1,563.1)	2.7
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	(70.1)								(70.1)
Unrealized loss on available-for-sale securities	(0.8)									(0.8)
Comprehensive loss	(70.9)
Tax withholding on vested equity awards	(22.5)						(22.5)
Stock-based compensation	15.6						15.6
Exercise of stock options and issuance of shares (shares)					495
Exercise of stock options and issuance of shares	0.7						0.7
Balance at end of period (shares) at Sep. 26, 2021					116,186
Balance at end of period at Sep. 26, 2021	$ 2,039.4				$ 0.1		3,670.6		(1,633.2)	1.9
Balance at beginning of period (shares) at Jun. 27, 2021	115,691				115,691
Balance at beginning of period at Jun. 27, 2021	$ 2,116.5				$ 0.1		3,676.8		(1,563.1)	2.7
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	(233.3)
Unrealized loss on available-for-sale securities	(20.7)
Comprehensive loss	$ (254.0)
Balance at end of period (shares) at Mar. 27, 2022	123,599				123,599
Balance at end of period at Mar. 27, 2022	$ 2,390.4				$ 0.2		4,204.6		(1,796.4)	(18.0)
Balance at beginning of period (shares) at Sep. 26, 2021					116,186
Balance at beginning of period at Sep. 26, 2021	2,039.4				$ 0.1		3,670.6		(1,633.2)	1.9
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	(96.7)								(96.7)
Unrealized loss on available-for-sale securities	(3.6)									(3.6)
Comprehensive loss	(100.3)
Tax withholding on vested equity awards	(2.8)						(2.8)
Stock-based compensation	15.7						15.7
Exercise of stock options and issuance of shares (shares)					258
Exercise of stock options and issuance of shares	10.7						10.7
Issuance of shares related to the extinguishment of convertible notes due September 1, 2023 (in shares)					7,126
Issuance of shares related to the extinguishment of convertible notes due September 1, 2023	416.2				$ 0.1		416.1
Balance at end of period (shares) at Dec. 26, 2021					123,570
Balance at end of period at Dec. 26, 2021	2,378.9				$ 0.2		4,110.3		(1,729.9)	(1.7)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	(66.5)								(66.5)
Unrealized loss on available-for-sale securities	(16.3)									(16.3)
Comprehensive loss	(82.8)
Tax withholding on vested equity awards	(0.8)						(0.8)
Stock-based compensation	15.4						15.4
Exercise of stock options and issuance of shares (shares)					29	0
Exercise of stock options and issuance of shares	0.3	$ (108.2)					0.3	$ (108.2)
Issuance of convertible notes due February 15, 2028	$ 187.6						187.6
Balance at end of period (shares) at Mar. 27, 2022	123,599				123,599
Balance at end of period at Mar. 27, 2022	$ 2,390.4				$ 0.2		$ 4,204.6		$ (1,796.4)	$ (18.0)