Business Combinations - Summary of Fair Values of Tangible Assets Acquired, Liabilities Assumed, Intangible Assets and Residual Goodwill (Detail) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2016	Dec. 31, 2015	[1]
Business Acquisition [Line Items]
Goodwill	$ 19,512	$ 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	$ 2,641
Liabilities assumed	(3,476)
Goodwill	7,983
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.