Operating Segments and Geographic Information - Revenue by geographic area (Details) $ in Millions	3 Months Ended		6 Months Ended
	Dec. 29, 2018 USD ($) region	Dec. 30, 2017 USD ($)	Dec. 29, 2018 USD ($) region	Dec. 30, 2017 USD ($)
Information on reportable segments
Number of geographic regions | region	3		3
Total net revenue	$ 306.9	$ 205.4	$ 575.4	$ 396.3
Product revenue
Information on reportable segments
Total net revenue	272.8	181.3	513.9	346.4
Service revenue
Information on reportable segments
Total net revenue	34.1	24.1	61.5	49.9
United States
Information on reportable segments
Total net revenue	104.1	90.3	176.9	167.9
United States | Product revenue
Information on reportable segments
Total net revenue	89.8	76.5	149.9	141.1
United States | Service revenue
Information on reportable segments
Total net revenue	14.3	13.8	27.0	26.8
Other Americas
Information on reportable segments
Total net revenue	21.3	23.7	42.3	40.7
Other Americas | Product revenue
Information on reportable segments
Total net revenue	17.3	20.1	35.2	32.1
Other Americas | Service revenue
Information on reportable segments
Total net revenue	4.0	3.6	7.1	8.6
Total Americas
Information on reportable segments
Total net revenue	125.4	114.0	219.2	208.6
Total Americas | Product revenue
Information on reportable segments
Total net revenue	107.1	96.6	185.1	173.2
Total Americas | Service revenue
Information on reportable segments
Total net revenue	18.3	17.4	34.1	35.4
Greater China
Information on reportable segments
Total net revenue	66.9	29.1	125.8	52.1
Greater China | Product revenue
Information on reportable segments
Total net revenue	64.8	28.7	123.5	51.1
Greater China | Service revenue
Information on reportable segments
Total net revenue	2.1	0.4	2.3	1.0
Other Asia
Information on reportable segments
Total net revenue	34.0	16.8	73.5	31.0
Other Asia | Product revenue
Information on reportable segments
Total net revenue	30.4	15.9	66.4	29.0
Other Asia | Service revenue
Information on reportable segments
Total net revenue	3.6	0.9	7.1	2.0
Total Asia-Pacific
Information on reportable segments
Total net revenue	100.9	45.9	199.3	83.1
Total Asia-Pacific | Product revenue
Information on reportable segments
Total net revenue	95.2	44.6	189.9	80.1
Total Asia-Pacific | Service revenue
Information on reportable segments
Total net revenue	5.7	1.3	9.4	3.0
Switzerland
Information on reportable segments
Total net revenue	23.0	12.2	48.7	40.5
Switzerland | Product revenue
Information on reportable segments
Total net revenue	23.0	12.2	48.7	40.5
Switzerland | Service revenue
Information on reportable segments
Total net revenue	0.0	0.0	0.0	0.0
Other EMEA
Information on reportable segments
Total net revenue	57.6	33.3	108.2	64.1
Other EMEA | Product revenue
Information on reportable segments
Total net revenue	47.5	27.9	90.2	52.6
Other EMEA | Service revenue
Information on reportable segments
Total net revenue	10.1	5.4	18.0	11.5
Total EMEA
Information on reportable segments
Total net revenue	80.6	45.5	156.9	104.6
Total EMEA | Product revenue
Information on reportable segments
Total net revenue	70.5	40.1	138.9	93.1
Total EMEA | Service revenue
Information on reportable segments
Total net revenue	$ 10.1	$ 5.4	$ 18.0	$ 11.5