Segments - Revenues by Customer Vertical (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Segment Reporting Information [Line Items]
Total net revenues	$ 1,138.2	$ 1,133.1	$ 3,222.5	$ 3,237.3
Cloud
Segment Reporting Information [Line Items]
Total net revenues	253.1	271.9	800.5	780.0
Service Provider
Segment Reporting Information [Line Items]
Total net revenues	475.1	452.5	1,286.8	1,335.3
Enterprise
Segment Reporting Information [Line Items]
Total net revenues	$ 410.0	$ 408.7	$ 1,135.2	$ 1,122.0