Operating Segments and Geographic Information - Information on Reportable Segments (Details) $ in Millions	3 Months Ended		9 Months Ended
	Mar. 28, 2020 USD ($)	Mar. 30, 2019 USD ($)	Mar. 28, 2020 USD ($) segment	Mar. 30, 2019 USD ($)
Information on reportable segments
Number of broad business categories (in segment) | segment			2
Total net revenue	$ 256.2	$ 265.2	$ 869.7	$ 840.6
Gross profit	$ 146.8	$ 153.5	$ 510.7	$ 481.9
Gross margin (as a percent)	57.30%	57.90%	58.70%	57.30%
Operating income	$ 9.1	$ 7.9	$ 74.8	$ 39.6
Operating margin (as a percent)	3.60%	3.00%	8.60%	4.70%
Other Items
Information on reportable segments
Total net revenue	$ 0.0	$ 0.0	$ 0.0	$ 0.0
Gross profit	(9.9)	(9.0)	(29.1)	(29.0)
Operating income	(28.9)	(31.1)	(83.8)	(107.1)
Network and Service Enablement | Segment Measures
Information on reportable segments
Total net revenue	187.0	205.4	641.0	619.8
Gross profit	$ 120.3	$ 131.7	$ 416.5	$ 398.9
Gross margin (as a percent)	64.30%	64.10%	65.00%	64.40%
Operating income	$ 13.8	$ 20.7	$ 73.6	$ 69.9
Operating margin (as a percent)	7.40%	10.10%	11.50%	11.30%
Network and Service Enablement | Network Enablement | Segment Measures
Information on reportable segments
Total net revenue	$ 163.9	$ 180.5	$ 565.8	$ 540.5
Gross profit	$ 104.3	$ 115.8	$ 367.1	$ 344.4
Gross margin (as a percent)	63.60%	64.20%	64.90%	63.70%
Network and Service Enablement | Service Enablement | Segment Measures
Information on reportable segments
Total net revenue	$ 23.1	$ 24.9	$ 75.2	$ 79.3
Gross profit	$ 16.0	$ 15.9	$ 49.4	$ 54.5
Gross margin (as a percent)	69.30%	63.90%	65.70%	68.70%
Optical Security and Performance Products | Segment Measures
Information on reportable segments
Total net revenue	$ 69.2	$ 59.8	$ 228.7	$ 220.8
Gross profit	$ 36.4	$ 30.8	$ 123.3	$ 112.0
Gross margin (as a percent)	52.60%	51.50%	53.90%	50.70%
Operating income	$ 24.2	$ 18.3	$ 85.0	$ 76.8
Operating margin (as a percent)	35.00%	30.60%	37.20%	34.80%
Product revenue
Information on reportable segments
Total net revenue	$ 223.8	$ 232.1	$ 770.5	$ 746.0
Product revenue | Other Items
Information on reportable segments
Total net revenue	0.0	0.0	0.0	0.0
Product revenue | Network and Service Enablement | Segment Measures
Information on reportable segments
Total net revenue	154.6	172.4	542.1	525.7
Product revenue | Network and Service Enablement | Network Enablement | Segment Measures
Information on reportable segments
Total net revenue	146.0	160.8	507.2	486.7
Product revenue | Network and Service Enablement | Service Enablement | Segment Measures
Information on reportable segments
Total net revenue	8.6	11.6	34.9	39.0
Product revenue | Optical Security and Performance Products | Segment Measures
Information on reportable segments
Total net revenue	69.2	59.7	228.4	220.3
Service revenue
Information on reportable segments
Total net revenue	32.4	33.1	99.2	94.6
Service revenue | Other Items
Information on reportable segments
Total net revenue	0.0	0.0	0.0	0.0
Service revenue | Network and Service Enablement | Segment Measures
Information on reportable segments
Total net revenue	32.4	33.0	98.9	94.1
Service revenue | Network and Service Enablement | Network Enablement | Segment Measures
Information on reportable segments
Total net revenue	17.9	19.7	58.6	53.8
Service revenue | Network and Service Enablement | Service Enablement | Segment Measures
Information on reportable segments
Total net revenue	14.5	13.3	40.3	40.3
Service revenue | Optical Security and Performance Products | Segment Measures
Information on reportable segments
Total net revenue	$ 0.0	$ 0.1	$ 0.3	$ 0.5