Other Financial Information, Other Income (Expense), Net (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Other Financial Information [Abstract]
Interest income	$ 6.7	$ 2.1	$ 10.5	$ 4.2
Interest expense	(21.8)	(17.8)	(40.3)	(33.3)
Net gain on legal settlement	0.0	195.3	0.0	195.3
Gain on investments	0.2	0.8	0.8	167.0
Other	(2.2)	(1.8)	(3.9)	(0.4)
Other (expense) income, net	(17.1)	178.6	(32.9)	332.8
Gain Contingencies [Line Items]
Net gain on legal settlement	$ 0.0	195.3	$ 0.0	195.3
Publicly-traded equity and privately-held investments, net realized gain				$ 163.0
Palo Alto Networks [Member]
Gain Contingencies [Line Items]
Proceeds from legal settlements		$ 75.0