Other Financial Information, Deferred Revenue (Details) - USD ($) $ in Millions	Mar. 31, 2016	Dec. 31, 2015
Deferred revenue:
Total deferred revenue	$ 1,260.0	$ 1,168.1
Reported as:
Current	893.3	822.9
Long-term	366.7	345.2
Total deferred revenue	1,260.0	1,168.1
Sales Revenue, Product, Net [Member]
Deferred revenue:
Undelivered product commitments and other product deferrals	205.6	210.1
Distributor inventory and other sell-through items	102.8	81.8
Deferred gross product revenue	308.4	291.9
Deferred cost of product revenue	(47.3)	(51.6)
Total deferred revenue	261.1	240.3
Reported as:
Total deferred revenue	261.1	240.3
Sales Revenue, Service, Net [Member]
Deferred revenue:
Total deferred revenue	998.9	927.8
Reported as:
Total deferred revenue	$ 998.9	$ 927.8