Accumulated Other Comprehensive Loss (Details) - USD ($)	12 Months Ended
	Jun. 29, 2019	Jun. 30, 2018	Jul. 01, 2017
Changes in accumulated other comprehensive income (loss) by component
Beginning balance	$ 734,900,000	$ 803,500,000	$ 689,300,000
Other comprehensive (loss) income before reclassification	(34,000,000.0)
Amounts reclassified from accumulated other comprehensive (loss) income	2,300,000
Net change in accumulated other comprehensive (loss) income	(31,700,000)	(10,300,000)	(102,400,000)
Ending balance	725,800,000	734,900,000	803,500,000
Unrealized actuarial loss	10,100,000
Income tax benefit	2,800,000
Available-for-sale securities | Lumentum
Changes in accumulated other comprehensive income (loss) by component
Tax impact from reclassification of gross realized gain from available-for-sale securities	0
Total
Changes in accumulated other comprehensive income (loss) by component
Beginning balance	(102,900,000)	(92,600,000)	10,000,000.0
Net change in accumulated other comprehensive (loss) income	(31,700,000)	(10,300,000)	(102,400,000)
Ending balance	(134,600,000)	(102,900,000)	$ (92,600,000)
Unrealized gains (losses) on available-for-sale investments
Changes in accumulated other comprehensive income (loss) by component
Beginning balance	(5,800,000)
Other comprehensive (loss) income before reclassification	300,000
Amounts reclassified from accumulated other comprehensive (loss) income	500,000
Net change in accumulated other comprehensive (loss) income	800,000
Ending balance	(5,000,000.0)	(5,800,000)
Foreign currency translation adjustments
Changes in accumulated other comprehensive income (loss) by component
Beginning balance	(74,000,000.0)
Other comprehensive (loss) income before reclassification	(27,000,000.0)
Amounts reclassified from accumulated other comprehensive (loss) income	0
Net change in accumulated other comprehensive (loss) income	(27,000,000.0)
Ending balance	(101,000,000.0)	(74,000,000.0)
Change in unrealized components of defined benefit obligations, net of tax
Changes in accumulated other comprehensive income (loss) by component
Beginning balance	(23,100,000)
Other comprehensive (loss) income before reclassification	(7,300,000)
Amounts reclassified from accumulated other comprehensive (loss) income	1,800,000
Net change in accumulated other comprehensive (loss) income	(5,500,000)
Ending balance	$ (28,600,000)	$ (23,100,000)