Segments - Revenues by Customer Vertical (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Segment Reporting Information [Line Items]
Total net revenues	$ 1,308.9	$ 1,221.3	$ 2,529.9	$ 2,319.2
Cloud
Segment Reporting Information [Line Items]
Total net revenues	379.6	287.3	711.2	552.1
Telecom/Cable
Segment Reporting Information [Line Items]
Total net revenues	562.4	571.0	1,130.9	1,089.1
Strategic Enterprise
Segment Reporting Information [Line Items]
Total net revenues	$ 366.9	$ 363.0	$ 687.8	$ 678.0