Business Combinations - Intangible Assets Acquired (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
128 Technology
Business Acquisition [Line Items]
Total intangible assets acquired	$ 116.7
128 Technology | Existing technology
Business Acquisition [Line Items]
Weighted Average Estimated Useful Life (In Years)	5 years
Total intangible assets acquired	$ 88.0
128 Technology | Customer relationships
Business Acquisition [Line Items]
Weighted Average Estimated Useful Life (In Years)	5 years
Total intangible assets acquired	$ 27.0
128 Technology | Backlog
Business Acquisition [Line Items]
Weighted Average Estimated Useful Life (In Years)	1 year 6 months
Total intangible assets acquired	$ 1.7
Netrounds
Business Acquisition [Line Items]
Total intangible assets acquired	$ 8.7
Netrounds | Existing technology
Business Acquisition [Line Items]
Weighted Average Estimated Useful Life (In Years)	4 years
Total intangible assets acquired	$ 5.3
Netrounds | Customer relationships
Business Acquisition [Line Items]
Weighted Average Estimated Useful Life (In Years)	5 years
Total intangible assets acquired	$ 3.4
Mist
Business Acquisition [Line Items]
Total intangible assets acquired		$ 102.0
Mist | Existing technology
Business Acquisition [Line Items]
Weighted Average Estimated Useful Life (In Years)		5 years
Total intangible assets acquired		$ 81.0
Mist | Customer relationships
Business Acquisition [Line Items]
Weighted Average Estimated Useful Life (In Years)		5 years
Total intangible assets acquired		$ 15.0
Mist | Trade name
Business Acquisition [Line Items]
Weighted Average Estimated Useful Life (In Years)		5 years
Total intangible assets acquired		$ 6.0