Other Financial Information - Notes Receivable and Deposit, Revenue, Deferred Commissions Narrative (Details) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Disaggregation of Revenue [Line Items]
Proceeds from pulse note receivable	$ 50,000,000.0	$ 0	$ 0
Non-interest bearing deposit to contract manufacturer	43,600,000
Non-interest bearing deposit to contract manufacturer, unamortized discount	$ 1,600,000
Non-interest bearing deposit to contract manufacturer, imputed interest rate	5.00%
Impairment charge, notes receivable	$ 0	0	$ 0
Deferred commission	27,400,000	24,100,000
Amortization of deferred commission	145,900,000	$ 130,900,000
Impairment loss	0
Product
Disaggregation of Revenue [Line Items]
Contract with customer, liability, revenue recognized	72,300,000
Service
Disaggregation of Revenue [Line Items]
Contract with customer, liability, revenue recognized	717,300,000
Junos Pulse
Disaggregation of Revenue [Line Items]
Proceeds from collection of notes receivable, principal	50,000,000.0
Proceeds from collection of notes receivable, accrued interest	37,700,000
Proceeds from collection of notes receivable, other payments	4,100,000
Proceeds from pulse note receivable	$ 91,800,000