Revenue Recognition - Disaggregated Revenues (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Disaggregation of Revenue [Line Items]
Total revenue	$ 615.5	$ 521.7	$ 1,192.4	$ 994.3
Product [Member]
Disaggregation of Revenue [Line Items]
Total revenue	211.9	189.9	404.2	352.6
Service [Member]
Disaggregation of Revenue [Line Items]
Total revenue	403.6	331.8	788.2	641.7
Security Subscription [Member]
Disaggregation of Revenue [Line Items]
Total revenue	222.6	183.1	434.0	352.7
Technical Support and Other [Member]
Disaggregation of Revenue [Line Items]
Total revenue	$ 181.0	$ 148.7	$ 354.2	$ 289.0