Investments - Short-term Investments by Type (Details) - USD ($) $ in Millions	Mar. 29, 2020	Jun. 30, 2019
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	$ 529.1	$ 548.4
Gross Unrealized Gains	3.2	2.6
Gross Unrealized Losses	(2.4)	(0.1)
Estimated Fair Value	529.9	550.9
Municipal bonds
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	74.3	78.2
Gross Unrealized Gains	0.7	0.4
Gross Unrealized Losses	(0.2)	(0.1)
Estimated Fair Value	74.8	78.5
Corporate bonds
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	315.3	256.0
Gross Unrealized Gains	0.9	1.0
Gross Unrealized Losses	(2.2)	0.0
Estimated Fair Value	314.0	257.0
U.S. agency securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	21.5	25.6
Gross Unrealized Gains	0.1	0.0
Gross Unrealized Losses	0.0	0.0
Estimated Fair Value	21.6	25.6
U.S. treasury securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	68.8	92.4
Gross Unrealized Gains	0.8	0.1
Gross Unrealized Losses	0.0	0.0
Estimated Fair Value	69.6	92.5
Certificates of deposit | Non-US
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	31.8	49.1
Gross Unrealized Gains	0.7	1.1
Gross Unrealized Losses	0.0	0.0
Estimated Fair Value	32.5	50.2
Certificates of deposit | United States
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	5.2	22.4
Gross Unrealized Gains	0.0	0.0
Gross Unrealized Losses	0.0	0.0
Estimated Fair Value	5.2	22.4
Variable rate demand note
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	2.5	16.9
Gross Unrealized Gains	0.0	0.0
Gross Unrealized Losses	0.0	0.0
Estimated Fair Value	2.5	16.9
Commercial paper
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	9.7	7.8
Gross Unrealized Gains	0.0	0.0
Gross Unrealized Losses	0.0	0.0
Estimated Fair Value	$ 9.7	$ 7.8