Operating Segments and Geographic Information - Information on Reportable Segments (Details) $ in Millions	3 Months Ended
	Sep. 29, 2018 USD ($) segment	Sep. 30, 2017 USD ($)
Information on reportable segments
Number of broad business categories (in segment) | segment	2
Total net revenue	$ 268.5	$ 190.9
Gross profit	$ 150.4	$ 112.7
Gross margin (as a percent)	56.00%	59.00%
Operating income	$ (1.2)	$ 6.7
Operating margin (as a percent)	(0.40%)	3.50%
Other Items
Information on reportable segments
Total net revenue	$ 0.0	$ 0.0
Gross profit	(10.2)	(6.3)
Operating income	(45.0)	(19.4)
Network and Service Enablement | Segment Measures
Information on reportable segments
Total net revenue	190.7	136.5
Gross profit	$ 121.2	$ 87.6
Gross margin (as a percent)	63.60%	64.20%
Operating income	$ 16.4	$ 3.9
Operating margin (as a percent)	8.60%	2.90%
Network and Service Enablement | Network Enablement | Segment Measures
Information on reportable segments
Total net revenue	$ 164.5	$ 111.6
Gross profit	$ 102.9	$ 70.3
Gross margin (as a percent)	62.60%	63.00%
Network and Service Enablement | Service Enablement | Segment Measures
Information on reportable segments
Total net revenue	$ 26.2	$ 24.9
Gross profit	$ 18.3	$ 17.3
Gross margin (as a percent)	69.80%	69.50%
Optical Security and Performance Products | Segment Measures
Information on reportable segments
Total net revenue	$ 77.8	$ 54.4
Gross profit	$ 39.4	$ 31.4
Gross margin (as a percent)	50.60%	57.70%
Operating income	$ 27.4	$ 22.2
Operating margin (as a percent)	35.20%	40.80%
Product
Information on reportable segments
Total net revenue	$ 241.1	$ 165.1
Product | Other Items
Information on reportable segments
Total net revenue	0.0	0.0
Product | Network and Service Enablement | Segment Measures
Information on reportable segments
Total net revenue	163.5	111.4
Product | Network and Service Enablement | Network Enablement | Segment Measures
Information on reportable segments
Total net revenue	149.9	102.8
Product | Network and Service Enablement | Service Enablement | Segment Measures
Information on reportable segments
Total net revenue	13.6	8.6
Product | Optical Security and Performance Products | Segment Measures
Information on reportable segments
Total net revenue	77.6	53.7
Service
Information on reportable segments
Total net revenue	27.4	25.8
Service | Other Items
Information on reportable segments
Total net revenue	0.0	0.0
Service | Network and Service Enablement | Segment Measures
Information on reportable segments
Total net revenue	27.2	25.1
Service | Network and Service Enablement | Network Enablement | Segment Measures
Information on reportable segments
Total net revenue	14.6	8.8
Service | Network and Service Enablement | Service Enablement | Segment Measures
Information on reportable segments
Total net revenue	12.6	16.3
Service | Optical Security and Performance Products | Segment Measures
Information on reportable segments
Total net revenue	$ 0.2	$ 0.7