Income Taxes (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jan. 02, 2016	Dec. 27, 2014	Jan. 02, 2016	Dec. 27, 2014	Oct. 03, 2015	Jun. 27, 2015
Income Tax Disclosure [Abstract]
(Benefit from) provision for income taxes	$ (1.2)	$ 8.5	$ (0.4)	$ 14.3
Valuation Allowance [Line Items]
Reclassification out of current deferred tax liabilities	0.0		0.0			$ (7.1)
Unrecognized tax benefits	37.0		37.0			$ 37.4
Interest and penalties accrued	1.6		1.6
Unrecognized tax benefits that may be recognized during the next twelve months	0.1		0.1
Effect of Early Adoption of Authoritative Guidance on Balance Sheet Classification of Deferred Taxes
Valuation Allowance [Line Items]
Reclassification out of current deferred tax assets					$ 3.1
Increase in noncurrent deferred tax assets					3.1
Reclassification out of current deferred tax liabilities					0.7
Increase in noncurrent deferred tax liabilities					$ 0.7
Increase in Lumentum valuation allowance
Valuation Allowance [Line Items]
Onetime increase in valuation allowance immediately before the separation transaction			8.9
Continuing operations
Valuation Allowance [Line Items]
Tax benefit from discontinued operations	$ 8.8		$ 22.2