Earnings Per Share - Computation of Basic and Diluted Net Income (Loss) Per Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended								9 Months Ended	12 Months Ended
	Jun. 29, 2019	Mar. 30, 2019	Dec. 29, 2018	Sep. 29, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 30, 2017	Sep. 30, 2017	Mar. 31, 2018	Jun. 29, 2019	Jun. 30, 2018	Jul. 01, 2017
Numerator:
Income (loss) from continuing operations, net of taxes	$ 12.5	$ (4.8)	$ 15.4	$ (15.3)	$ (29.2)	$ (10.7)	$ (1.1)	$ (7.6)	$ (48.6)	$ 7.8	$ (48.6)	$ 158.6
(Loss) income from discontinued operations, net of taxes	0.0	0.0	(2.4)	0.0	0.0	0.0	0.0	0.0	$ 0.0	(2.4)	0.0	1.6
Net income (loss)	$ 12.5	$ (4.8)	$ 13.0	$ (15.3)	$ (29.2)	$ (10.7)	$ (1.1)	$ (7.6)		$ 5.4	$ (48.6)	$ 160.2
Weighted-average shares outstanding:
Basic (in shares)	228.7	228.3	228.3	227.2	226.5	226.3	227.4	228.1		228.1	227.1	229.9
Effect of dilutive securities from stock-based benefit plans (in shares)										3.1	0.0	4.6
Diluted (in shares)	232.5	228.3	230.4	227.2	226.5	226.3	227.4	228.1		231.2	227.1	234.5
Net income (loss) per share from - basic:
Continuing operations (usd per share)	$ 0.05	$ (0.02)	$ 0.07	$ (0.07)	$ (0.13)	$ (0.05)	$ 0	$ (0.03)		$ 0.03	$ (0.21)	$ 0.69
Discontinued operations (usd per share)	0	0	(0.01)	0	0	0	0	0		(0.01)	0	0.01
Net income (loss) (usd per share)	0.05	(0.02)	0.06	(0.07)	(0.13)	(0.05)	0	(0.03)		0.02	(0.21)	0.70
Net income (loss) per share from - diluted:
Continuing operations (usd per share)	0.05	(0.02)	0.07	(0.07)	(0.13)	(0.05)	0	(0.03)		0.03	(0.21)	0.68
Discontinued operations (usd per share)	0	0	(0.01)	0	0	0	0	0		(0.01)	0	0
Net income (loss) (usd per share)	$ 0.05	$ (0.02)	$ 0.06	$ (0.07)	$ (0.13)	$ (0.05)	$ 0	$ (0.03)		$ 0.02	$ (0.21)	$ 0.68