Goodwill and Acquired Intangible Assets - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Finite Lived Intangible Assets [Line Items]
Goodwill acquired	$ 2,476,000
Intangible assets acquired	12,478,000	$ 10,668,000
Impairment of goodwill	0
Amortization of acquired intangibles	$ 1,408,000	1,408,000	$ 1,269,000
Estimated useful life	7 years
Weighted average useful lives of acquired technology intangible assets	5 years 6 months
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]
Intangible assets acquired	$ 11,718,000	10,668,000
Weighted average useful lives of acquired technology intangible assets	5 years 2 months 12 days
Customer Relationships [Member]
Finite Lived Intangible Assets [Line Items]
Intangible assets acquired	$ 480,000
Weighted average useful lives of acquired technology intangible assets	7 years
Trade Name and Other [Member]
Finite Lived Intangible Assets [Line Items]
Intangible assets acquired	$ 280,000
Weighted average useful lives of acquired technology intangible assets	7 years
Camouflage Software, Inc [Member]
Finite Lived Intangible Assets [Line Items]
Goodwill acquired	$ 2,500,000
Intangible assets acquired	1,800,000
Impairment of goodwill	$ 0	$ 0	$ 0