Other Financial Information - Deferred Revenue (Details) - USD ($) $ in Millions	Sep. 30, 2019	Dec. 31, 2018
Reported as:
Current	$ 741.6	$ 829.3
Long-term	377.1	384.3
Deferred revenue	1,118.7	1,213.6
Undelivered product commitments and other product deferrals
Deferred product revenue:
Deferred gross product revenue	138.4	163.3
Product
Deferred product revenue:
Deferred gross product revenue	138.4	163.3
Deferred cost of product revenue	(9.4)	(18.9)
Reported as:
Deferred revenue	129.0	144.4
Service
Reported as:
Deferred revenue	$ 989.7	$ 1,069.2