Investments, Forward Contracts and Fair Value Measurements - Available for Sale Securities Reconciliation (Details) - USD ($) $ in Millions	Sep. 29, 2018	Jun. 30, 2018
Available-for-sale Debt Securities [Abstract]
Amortized Cost/ Carrying Cost	$ 51.5	$ 190.8
Gross Unrealized Gains	0.0	0.0
Gross Unrealized Losses	(0.8)	(1.2)
Fair Value	50.7	189.6
U.S. treasuries
Available-for-sale Debt Securities [Abstract]
Amortized Cost/ Carrying Cost	4.0	36.0
Gross Unrealized Gains	0.0	0.0
Gross Unrealized Losses	0.0	(0.1)
Fair Value	4.0	35.9
U.S. agencies
Available-for-sale Debt Securities [Abstract]
Amortized Cost/ Carrying Cost	8.8	13.3
Gross Unrealized Gains	0.0	0.0
Gross Unrealized Losses	(0.1)	(0.1)
Fair Value	8.7	13.2
Municipal bonds and sovereign debt instruments
Available-for-sale Debt Securities [Abstract]
Amortized Cost/ Carrying Cost	2.7	2.7
Gross Unrealized Gains	0.0	0.0
Gross Unrealized Losses	0.0	0.0
Fair Value	2.7	2.7
Asset-backed securities
Available-for-sale Debt Securities [Abstract]
Amortized Cost/ Carrying Cost	7.0	23.9
Gross Unrealized Gains	0.0	0.0
Gross Unrealized Losses	(0.3)	(0.4)
Fair Value	6.7	23.5
Corporate securities
Available-for-sale Debt Securities [Abstract]
Amortized Cost/ Carrying Cost	29.0	114.9
Gross Unrealized Gains	0.0	0.0
Gross Unrealized Losses	(0.4)	(0.6)
Fair Value	$ 28.6	$ 114.3

Amount, before tax, of unrealized gain in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27161-111563

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Amount, before tax, of unrealized loss in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

+ References

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-Publisher FASB
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Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

+ References

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
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-Section 50
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Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 45
-Paragraph 1
-Subparagraph (b)
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