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Balance Sheet Components - Goodwill (Details) - USD ($)	9 Months Ended
Balance Sheet Components - Goodwill (Details) - USD ($)	Sep. 30, 2020	Sep. 30, 2019	Jan. 31, 2020	Dec. 31, 2019
Indefinite-lived Intangible Assets [Line Items]
Goodwill	$ 17,167,000			$ 4,083,000
Goodwill, impairment loss	0	$ 0
S2 Systems Corporation
Indefinite-lived Intangible Assets [Line Items]
Goodwill			$ 13,084,000
Goodwill acquired during period	$ 13,100,000