Subsequent Events (Details) (USD $) Share data in Millions, except Per Share data, unless otherwise specified	0 Months Ended	3 Months Ended	6 Months Ended			0 Months Ended		1 Months Ended	3 Months Ended	0 Months Ended
	Feb. 20, 2014	Jun. 30, 2013	Jun. 30, 2013	Jun. 30, 2014	Dec. 31, 2013	Jul. 22, 2014 Subsequent Event [Member]	Jul. 22, 2014 Subsequent Event [Member]	Aug. 11, 2014 Subsequent Event [Member]	Jun. 30, 2014 2014 Stock Repurchase Program [Member]	Jul. 23, 2014 2014 Stock Repurchase Program [Member] Subsequent Event [Member]
Subsequent Event [Line Items]
Sale of Junos Pulse, Amount							$ 250,000,000
Goodwill				4,071,500,000	4,057,700,000		160,400,000
Deferred Revenue				(1,173,300,000)	(1,069,300,000)		(45,600,000)
Purchased intangible assets, net				105,300,000	106,900,000		6,000,000
Other, net							3,900,000
Total net assets for Pulse							124,700,000
Intended quarterly cash dividend based on most recent announcement (in dollars per share)	$ 0.10					$ 0.10	$ 0.10
Stock Repurchased During Period, Shares								12.8
Stock Repurchased During Period, Value								300,000,000
Common Stock Repurchased Under Stock Repurchase Program Average Purchase Price		$ 16.45	$ 18.68					$ 23.38
Stock Repurchased and Retired During Period, Shares		6.4	12.6					10.7	33.3
Stock Repurchase Program, Remaining Authorized Repurchase Amount								500,000,000	800,000,000
Sale of Junos Pulse, Amount Related to Cash							125,000,000
Sale of Junos Pulse, Amount Related to Promissory Note							$ 125,000,000
Stock Repurchased under ASR, Shares										16.0
Total Stock Repurchased under ASR										49.3
Common Stock Repurchased Under ASR Average Purchase Price										$ 24.35
Stock Repurchased under ASR, Shares To Be Retired										16.0