Balance Sheet and Other Details (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Jul. 02, 2016	Apr. 02, 2016	Dec. 26, 2015	Sep. 26, 2015	Jun. 27, 2015	Mar. 28, 2015	Dec. 27, 2014	Sep. 27, 2014	Jul. 02, 2016	Jun. 27, 2015	Jun. 28, 2014
Accounts receivable allowance
Accounts receivable allowance	$ (0.9)				$ (1.2)				$ (0.9)	$ (1.2)
Inventories
Finished goods	46.1				60.1				46.1	60.1
Work in process	25.5				23.4				25.5	23.4
Raw materials and purchased parts	29.0				16.2				29.0	16.2
Inventories	100.6				99.7				100.6	99.7
Prepayments and other current assets
Prepayments	33.7				20.4				33.7	20.4
Advances to contract manufacturers	10.3				9.5				10.3	9.5
Due from Viavi, net	2.0								2.0
Other current assets	15.3				16.2				15.3	16.2
Prepayments and other current assets	61.3				46.1				61.3	46.1
Property, plant and equipment
Property, plant and equipment, gross	518.2				416.2				518.2	416.2
Less: Accumulated depreciation	(334.8)				(273.0)				(334.8)	(273.0)
Property, plant and equipment, net	183.4				143.2				183.4	143.2
Depreciation expense									47.4	43.0	$ 35.5
Other current liabilities
Warranty accrual	2.8				2.8				2.8	2.8
Restructuring accrual and related charges	5.5				3.8				5.5	3.8
Others	3.8				4.8				3.8	4.8
Other current liabilities	12.1				11.4				12.1	11.4
Other non-current liabilities
Asset retirement obligation	2.3				1.8				2.3	1.8
Pension and related accrual	3.5				2.1				3.5	2.1
Deferred rent	1.6				1.7				1.6	1.7
Restructuring accrual and related charges	0.2				2.2				0.2	2.2
Other non-current liabilities	1.5				2.0				1.5	2.0
Other non-current liabilities	9.1				9.8				9.1	9.8
Interest and other income (expense), net
Interest expense									(0.1)	(0.7)	(0.2)
Foreign exchange gains (losses), net									(0.9)	(0.3)	1.6
Other income (expense), net									(0.2)	(0.1)	(0.3)
Interest and other income (expense), net	(0.1)	$ (0.4)	$ (0.5)	$ (0.2)	(0.3)	$ (0.4)	$ (0.1)	$ (0.3)	(1.2)	(1.1)	$ 1.1
Land
Property, plant and equipment
Property, plant and equipment, gross	5.9				5.9				5.9	5.9
Buildings and improvement
Property, plant and equipment
Property, plant and equipment, gross	28.9				28.6				28.9	28.6
Machinery and equipment
Property, plant and equipment
Property, plant and equipment, gross	378.5				326.4				378.5	326.4
Furniture and fixtures and software
Property, plant and equipment
Property, plant and equipment, gross	32.2				8.0				32.2	8.0
Leasehold improvements
Property, plant and equipment
Property, plant and equipment, gross	28.6				20.5				28.6	20.5
Construction in progress
Property, plant and equipment
Property, plant and equipment, gross	$ 44.1				$ 26.8				$ 44.1	$ 26.8