Segments (Details) $ in Millions	3 Months Ended
	Mar. 31, 2016 USD ($) segment	Mar. 31, 2015 USD ($)
Segment Reporting Information [Line Items]
Number of reportable segments | segment	1
Total net revenues	$ 1,097.9	$ 1,067.4
Routing [Member]
Segment Reporting Information [Line Items]
Total net revenues	504.1	504.8
Switching [Member]
Segment Reporting Information [Line Items]
Total net revenues	175.5	166.5
Security [Member]
Segment Reporting Information [Line Items]
Total net revenues	73.4	92.8
Total product [Member]
Segment Reporting Information [Line Items]
Total net revenues	753.0	764.1
Total service [Member]
Segment Reporting Information [Line Items]
Total net revenues	$ 344.9	$ 303.3