Other Financial Information - Deferred Revenue (Details) - USD ($) $ in Millions	Mar. 31, 2017	Dec. 31, 2016
Deferred product revenue:
Total deferred revenue	$ 1,493.0	$ 1,481.1
Reported as:
Current	992.5	1,032.0
Long-term	500.5	449.1
Total deferred revenue	1,493.0	1,481.1
Sales Revenue, Product, Net [Member]
Deferred product revenue:
Undelivered product commitments and other product deferrals	264.9	302.4
Distributor inventory and other sell-through items	68.7	74.2
Deferred gross product revenue	333.6	376.6
Deferred cost of product revenue	(52.3)	(53.7)
Total deferred revenue	281.3	322.9
Reported as:
Total deferred revenue	281.3	322.9
Sales Revenue, Service, Net [Member]
Deferred product revenue:
Total deferred revenue	1,211.7	1,158.2
Reported as:
Total deferred revenue	$ 1,211.7	$ 1,158.2