Goodwill and Acquired Intangible Assets - Additional Information (Detail) - USD ($)	1 Months Ended	3 Months Ended		9 Months Ended
	Feb. 28, 2017	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Finite Lived Intangible Assets [Line Items]
Goodwill allocated to disposal of assets				$ 1,059,000
Goodwill impairments		$ 0	$ 0	0	$ 0
Impairment of intangible assets		$ 0	$ 0	$ 0	$ 0
Minimum [Member]
Finite Lived Intangible Assets [Line Items]
Estimated useful life				7 years
Maximum [Member]
Finite Lived Intangible Assets [Line Items]
Estimated useful life				10 years
Acquired Technology [Member]
Finite Lived Intangible Assets [Line Items]
Weighted average remaining useful life				6 years 3 months 19 days
Customer Relationships [Member]
Finite Lived Intangible Assets [Line Items]
Weighted average remaining useful life				6 years 2 months 13 days
Trade Name and Other [Member]
Finite Lived Intangible Assets [Line Items]
Weighted average remaining useful life				6 years 2 months 13 days
Skyfence Cloud Access Security Broker Business [Member]
Finite Lived Intangible Assets [Line Items]
Goodwill allocated to disposal of assets	$ 1,100,000
Intangible assets derecognized in connection with disposal of assets	$ 4,500,000