Segments (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Segment Reporting Information [Line Items]
Total net revenues	$ 1,248.6	$ 1,125.9	$ 3,538.2	$ 3,525.5
Routing [Member]
Segment Reporting Information [Line Items]
Total net revenues	604.4	533.2	1,711.6	1,700.8
Switching [Member]
Segment Reporting Information [Line Items]
Total net revenues	201.4	155.0	558.1	546.8
Security [Member]
Segment Reporting Information [Line Items]
Total net revenues	119.6	121.3	319.5	367.1
Total product [Member]
Segment Reporting Information [Line Items]
Total net revenues	925.4	809.5	2,589.2	2,614.7
Total service [Member]
Segment Reporting Information [Line Items]
Total net revenues	$ 323.2	$ 316.4	$ 949.0	$ 910.8