Business Combination - Summary of Fair Values of Tangible Assets Acquired, Liabilities Assumed, Intangible Assets and Residual Goodwill (Detail) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2016	Dec. 31, 2015	[1]
Business Acquisition [Line Items]
Goodwill	$ 19,416	$ 19,417
Customer relationships [Member]
Business Acquisition [Line Items]
Intangible assets, Estimated Useful Life	4 years
SocialMoov [Member]
Business Acquisition [Line Items]
Tangible assets acquired	$ 2,741
Liabilities assumed	(3,480)
Goodwill	7,887
Total purchase price	$ 13,288
Goodwill, Estimated Useful Life	Indefinite
SocialMoov [Member] | Developed technology [Member]
Business Acquisition [Line Items]
Intangible assets, Estimated Fair Value	$ 3,800
Intangible assets, Estimated Useful Life	5 years
SocialMoov [Member] | Customer relationships [Member]
Business Acquisition [Line Items]
Intangible assets, Estimated Fair Value	$ 2,080
Intangible assets, Estimated Useful Life	4 years
SocialMoov [Member] | Tradename [Member]
Business Acquisition [Line Items]
Intangible assets, Estimated Fair Value	$ 260
Intangible assets, Estimated Useful Life	3 years

[1] Derived from our audited consolidated financial statements as of December 31, 2015.