Business Combinations - Purchase Price Allocation (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
128 Technology
Business Acquisition [Line Items]
Other assets acquired	$ 29.1
Goodwill	298.8
Intangible assets	116.7
Other assets acquired	14.3
Liabilities assumed	(10.7)
Total	448.2
Netrounds
Business Acquisition [Line Items]
Other assets acquired	1.0
Goodwill	24.7
Intangible assets	8.7
Other assets acquired	0.8
Liabilities assumed	(1.6)
Total	$ 33.6
Mist
Business Acquisition [Line Items]
Other assets acquired		$ 38.9
Goodwill		228.9
Intangible assets		102.0
Other assets acquired		15.8
Liabilities assumed		(26.4)
Total		$ 359.2