Commitments and Contingencies - Guarantees and Outstanding Letters of Credit and Performance Bonds (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Jun. 27, 2020	Mar. 28, 2020	Dec. 28, 2019	Sep. 28, 2019	Jun. 29, 2019	Mar. 30, 2019	Dec. 29, 2018	Sep. 29, 2018	Jun. 27, 2020	Jun. 29, 2019	Jun. 30, 2018
Loss Contingencies [Line Items]
Guarantee liabilities	$ 0.0				$ 0.0				$ 0.0	$ 0.0
Charge to discontinued operations	0.0	$ 0.0	$ 0.0	$ 0.0	$ 0.0	$ 0.0	$ 2.4	$ 0.0	0.0	$ 2.4	$ 0.0
Standby letters of credit
Loss Contingencies [Line Items]
Contingency	7.4								7.4
Performance bonds
Loss Contingencies [Line Items]
Contingency	$ 1.0								$ 1.0
Spinoff | Lumentum
Loss Contingencies [Line Items]
Charge to discontinued operations							$ 2.4