Investments - Contractual Maturities of Marketable Investments (Details) - USD ($) $ in Millions	Dec. 26, 2021	Jun. 27, 2021
Debt Securities, Available-for-sale [Line Items]
Within One Year	$ 122.3
After One, Within Five Years	360.9
After Five, Within Ten Years	0.0
After Ten Years	17.9
Total	501.1	$ 775.6
Municipal bonds
Debt Securities, Available-for-sale [Line Items]
Within One Year	36.4
After One, Within Five Years	96.8
After Five, Within Ten Years	0.0
After Ten Years	0.0
Total	133.2	141.3
Corporate bonds
Debt Securities, Available-for-sale [Line Items]
Within One Year	58.9
After One, Within Five Years	253.3
After Five, Within Ten Years	0.0
After Ten Years	0.0
Total	312.2	459.5
U.S. agency securities
Debt Securities, Available-for-sale [Line Items]
Within One Year	2.0
After One, Within Five Years	2.0
After Five, Within Ten Years	0.0
After Ten Years	0.0
Total	4.0	15.8
U.S. treasury securities
Debt Securities, Available-for-sale [Line Items]
Within One Year	4.0
After One, Within Five Years	8.8
After Five, Within Ten Years	0.0
After Ten Years	0.0
Total	12.8	72.5
Commercial paper
Debt Securities, Available-for-sale [Line Items]
Within One Year	21.0
After One, Within Five Years	0.0
After Five, Within Ten Years	0.0
After Ten Years	0.0
Total	21.0	50.0
Variable rate demand notes
Debt Securities, Available-for-sale [Line Items]
Within One Year	0.0
After One, Within Five Years	0.0
After Five, Within Ten Years	0.0
After Ten Years	17.9
Total	$ 17.9	$ 20.0