Operating Segments and Geographic Information - Information on Reportable Segments (Details) $ in Millions	3 Months Ended
	Oct. 03, 2020 USD ($) segment	Sep. 28, 2019 USD ($)
Information on reportable segments
Number of broad business categories (in segment) | segment	2
Total net revenue	$ 284.7	$ 299.8
Gross profit	$ 169.4	$ 174.4
Gross margin (as a percent)	59.50%	58.20%
Operating income	$ 31.3	$ 20.7
Operating margin (as a percent)	11.00%	6.90%
Other Items
Information on reportable segments
Total net revenue	$ 0.0	$ 0.0
Gross profit	(9.4)	(9.5)
Operating income	(29.3)	(32.0)
Network and Service Enablement | Segment Measures
Information on reportable segments
Total net revenue	183.5	219.8
Gross profit	$ 117.8	$ 140.6
Gross margin (as a percent)	64.20%	64.00%
Operating income	$ 13.3	$ 22.3
Operating margin (as a percent)	7.20%	10.10%
Network and Service Enablement | Network Enablement | Segment Measures
Information on reportable segments
Total net revenue	$ 162.1	$ 198.9
Gross profit	$ 103.5	$ 128.0
Gross margin (as a percent)	63.80%	64.40%
Network and Service Enablement | Service Enablement | Segment Measures
Information on reportable segments
Total net revenue	$ 21.4	$ 20.9
Gross profit	$ 14.3	$ 12.6
Gross margin (as a percent)	66.80%	60.30%
Optical Security and Performance Products | Segment Measures
Information on reportable segments
Total net revenue	$ 101.2	$ 80.0
Gross profit	$ 61.0	$ 43.3
Gross margin (as a percent)	60.30%	54.10%
Operating income	$ 47.3	$ 30.4
Operating margin (as a percent)	46.70%	38.00%
Product revenue
Information on reportable segments
Total net revenue	$ 247.9	$ 264.8
Product revenue | Other Items
Information on reportable segments
Total net revenue	0.0	0.0
Product revenue | Network and Service Enablement | Segment Measures
Information on reportable segments
Total net revenue	146.9	185.0
Product revenue | Network and Service Enablement | Network Enablement | Segment Measures
Information on reportable segments
Total net revenue	139.2	177.3
Product revenue | Network and Service Enablement | Service Enablement | Segment Measures
Information on reportable segments
Total net revenue	7.7	7.7
Product revenue | Optical Security and Performance Products | Segment Measures
Information on reportable segments
Total net revenue	101.0	79.8
Service revenue
Information on reportable segments
Total net revenue	36.8	35.0
Service revenue | Other Items
Information on reportable segments
Total net revenue	0.0	0.0
Service revenue | Network and Service Enablement | Segment Measures
Information on reportable segments
Total net revenue	36.6	34.8
Service revenue | Network and Service Enablement | Network Enablement | Segment Measures
Information on reportable segments
Total net revenue	22.9	21.6
Service revenue | Network and Service Enablement | Service Enablement | Segment Measures
Information on reportable segments
Total net revenue	13.7	13.2
Service revenue | Optical Security and Performance Products | Segment Measures
Information on reportable segments
Total net revenue	$ 0.2	$ 0.2