Other Financial Information - Deferred Revenue (Details) - USD ($) $ in Millions	Mar. 31, 2019	Dec. 31, 2018
Reported as:
Current	$ 860.1	$ 829.3
Long-term	370.8	384.3
Deferred revenue	1,230.9	1,213.6
Undelivered product commitments and other product deferrals
Deferred product revenue:
Deferred gross product revenue	152.3	163.3
Product
Deferred product revenue:
Deferred gross product revenue	152.3	163.3
Deferred cost of product revenue	(12.7)	(18.9)
Reported as:
Deferred revenue	139.6	144.4
Service
Reported as:
Deferred revenue	$ 1,091.3	$ 1,069.2